Right now all I can imagine is Vader seeing Boba's face for the first time and then having a full on panic attack like sobbing on the floor apologizing to Rex while a very confused Boba tries to comfort the sobbing Sith lord who is currently giving him a keldabe kiss and apologizing for not helping him more and not saving himself for him
Oh, now Nonny, what better way to ring in the colorful month of JUNE than with our favorite masked masochists! They sure do like to fight to be on top(giggity) but as per your request, Boba is going to reign supreme in this one. 😏 Pls forgib the delay on answering this ask, I hope part 4 finds you well!!
The Merc and the Moon
Part IV
Pairing: Darth Vader x Boba Fett
Warnings: (18+) smut, gay sex, anal sex, oral sex, come eating, hand jobs, glove/leather kink, authority kink, finger sucking, sinful uses of the Force.
Summary: Boba and Vader meet to do more than talk contracts.
Read on ao3 - 4.5k words - Parts 1/2/3
Writing Masterlist - My kofi✨
Boba would hate to admit to himself that he’s actually feeling the pangs of anxiety strike his heart. He and Vader haven’t spoken since their last engagement concerning the mishap with one Han Solo. He’s been contacted by the Dark Lord in regards to a specific job with the promise to be paid well.
As he waits for him to arrive, he notices the grit and grime of his last venture encrusted to his armor. Any common plebe would be rushing to the ‘fresher to make themselves presentable, but Boba’s identity lies in equal parts this deadly carapace as well as the blood that stains it.
However, it is taking a while for Vader to appear. There’s fashionably late, then there’s borderline impolite, not that Boba would hold him to such standards. For a bit, he considers the possibility that he’s been stood up, switching the holo-projector off to sit in silent darkness. It is in these still moments that a chirp can be heard at the entrance.
Boba taps a button on the panel of his bracer and the blast door slides open. He takes no action to greet his guest, keeping himself seated atop his shrouded throne. Vader steps in, tall and authoritative. His very presence is as alluring as it is intimidating. “Didn’t think you were going to show your mask in these parts.”
“I will admit, this is a rather sad hole in the wall you’ve summoned me to.” Vader’s boots hit the dusty flooring, hollow and resounding as he soon begins to circle around Boba.
“It’s secluded. Private.” Boba’s head turns to follow Vader’s gait. “Dark.”
Boba challenges him, making Vader think he was going to be the one calling the shots, but he is in the bounty hunter’s domain now. Vader’s path takes him through a tight coil as if he were circling a pipe with Boba as the drain. Boba stops him with a gloved hand just below his life support control panel, lifting his once relaxed arm from his chair to boldly make the initial contact. Vader humors Boba’s touch, suppressing the desire to barrel right through his arm at this impasse. “I take it you don’t care to talk contracts?”
“Sure, we can talk.” Boba pushes into him harder, his spread-out palm spanning over Vader’s mechanized stomach just above his waistline. He stands, the steel of his boots tapping together in a ringing chime with each advancement, backing Vader into the closest wall. “After.”
Vader tests his strength against Boba’s weakness in the way he’s shamelessly throwing himself at him, so he tastefully reminds this licensed killer of his station.
Vader collects the force around their bodies, concentrating it into a barrier between the two. Boba fights with the resistance, realizing he is being kept at bay. The visor secured to Boba’s helmet tilts on its axis as he turns his head, puzzled by Vader’s resistance. His labored breathing echoes through his modulator, a robotic inflection coating his every vowel and consonant. Vader spots a salacious flex of Boba’s neck muscles when his chest rises during this struggle, clearly seen beneath his layers of textile. Their illusive coverings hold a mystery that neither of them care to shatter, contrarily anchored by the need to be known and understood. “This is hardly equitable.”
“Equitable?” Boba strains his speech as Vader still has his phantom grip over him tightly. “I- argh… didn’t think you knew the meaning of the word.”
“I demand to see you.” Vader thinks of a way to even the playing field, ushering towards his own desires. “How long must you make me wait?”
“You’ve already seen me.” Boba was hoping to jump right into this, but Vader is requesting to take things slow.
“I might contend the same, however, we’d be here all night.” Vader quips back, rendering what Boba had just clarified redundant.
“As if you weren’t planning to do that from the start.” Boba calls Vader’s bluff and he curls his fingers inward a hair more to retaliate. The powerful restrictions holding Boba in place compress him deliciously. Where many would be unable to handle this treatment, Boba is exactly where he wants to be. “You don’t have to threaten me with a good time.”
“If it’s threats you want, threats I will make.” Vader’s open hand curls once again in warning. “Show yourself to me, lest you feel what happens when I close my fist.”
“You… say that like… it’s a bad thing.” Boba is taxed by the tension, unable to fill his lungs completely. His shallow breaths make him pant like an impudent hound and Vader finds his noises delectable. Boba is suspended inches above the ground, the tips of his boot soles barely graze the floor as he feels himself getting pushed a little over an arm’s length away.
The illusionary grip Vader has on him softens and Boba is afforded the ability to shed his first layer consisting of an ergonomic shirt with his upper armor secured right to the stitches. He carefully pulls it over his head, quickly replacing the helmet over his face while letting his pauldrons and plates fall where they lie in loud clangs to the floor. Next is his utility belt with which he teases Vader, acting like he can’t find the buckles for a few moments longer than what is socially necessary. A titular hiss comes from Vader’s direction when he grasps Boba’s mocking actions, smoothing out to his regular breathing when the belt thuds at his feet.
All that remains of course are his boots and kneeguards, forearm bracers and his precious codpiece veiling the very trophy Vader seeks within Boba’s flight suit.
“You are far from finished.” Vader scolds when Boba pauses his undressing.
“I hate to be the bearer of bad news, but there are just some things I won’t be taking off.” Boba advises, minimizing Vader’s expectations.
“A reasonable stipulation.” The hand still holding Boba in the air is stationary as his other one begins to rise, its strength concentrated on something lower than his bracers and helmet.
The codpiece.
The straps holding the plate secure are pulled taut and Boba’s groin begins to undergo a revolutionary onslaught as the tactile fasteners are stretched to extreme lengths until every last one snaps apart. “One that I care not to follow.”
It’s as if his palm has been magnetized that Vader promptly collects the triangular sheet of steel. Boba isn’t shocked that his fortitude includes obscene actions such as this. He’s more annoyed that he will be the one to repair that.
Vader holds the codpiece close to his shielded face, examining the details of its wear and tear. A polished section right at the center of the concave makes him chuckle as he surmises it has rubbed against Boba’s cock for years.
“I was using that.” Boba watches Vader indulge himself from afar, enticed by the swift absence of that item in particular.
“You’ve no need for it.” Vader disputes plainly, discarding it at his feet where the ringing clatter echoes into their collective ears. He waits for silence to fall again, a painstaking task that both of them seem to have the patience for. “Proceed.”
Boba shakes his head from side to side in feigned condemnation when Vader tests him. In spite of wanting to be the one to dictate what happens tonight, he does what is asked and begins unfastening the collar of his flight suit. With each section undone, Boba peels the fabric away to showcase his glistening chest, chiseled muscles catching what little light remains in the room.
With each row unfastened, Vader’s helmet tilts and sways, seeking every glimmer and flash of Boba’s taunting torso. The contours of his sculpted abdomen riddled with scars paint a delicious mosaic across his skin of all the times he’s been battered and beaten but survived. Vader admires him from where he stands, biting and moistening his dry, cracked lips from beneath his somber helm.
Vader bends the arm suspending Boba at the elbow and he soon senses himself drift forward, closing in towards the Dark Lord. From a few yards away, Boba at least felt some semblance of authority over things, but with this rapid advancement, it is clear that Vader has some games he is wanting to play first.
Boba closes in fast, unable to gauge the spike in velocity with the unanticipated near collision with Vader. He is stopped just short of running into him, a broadened mechanical fist halting his phantom induced advancements while still keeping Boba in mid air. His feet wiggle, expecting to come in contact with the ground but they just can’t reach.
Boba’s arms are still glued to his sides. The invisible bindings wrap around him like rope. Vader’s caught him in an impressive vice, examining him like a precious specimen before plunging a hand into Boba’s wide-open flight suit.
The mechanical digits grip Boba’s firm length, tightening against the buffer of leather and flesh. Boba chokes on his breath. Words get caught in his throat as he wrestles with this depraved attack. His enunciation falls apart into shuddered gasps and wanton groans with every precise stroke.
Boba has no recourse to fall back on but to receive all that is done to him. The secrecy of this setting paired with Vader’s impenitent proximity in keeping him restrained does wonders as Boba is brutishly worked over. He tries to cry out in protest, but Vader devises his own schemes against this by tightening his hold every time Boba squeaks.
The constriction of Vader encasing him manifests to a potent degree in Boba’s groin. The lack of space to move or even express his elation is forfeit as Vader continues to stroke until he sees Boba imitate a geyser. Ejaculate shoots from Boba’s tip, landing in random sequences all over Vader’s suit while also dirtying his gloves. The collected spend in his fist acts as an ideal lubricant to stroke him even after he’s released all that he could in this instance. Although, instead of Boba being embarrassed, he makes light of this happenstance.
“Lot faster than last time, I’ll give you that.” Boba pants breathlessly as Vader finally sets him on his feet. With shaky knees, he staggers away, treating Vader like a cheap fuck ready to toss him a tip and show him the door. “Thanks for dropping by.”
Vader uses his soiled hand to grab at Boba’s wrist. The smearing of viscous liquid saturates his arm and Boba is able to sense the heat radiating through his glove from his prosthetic appendages, reluctant to let go. “Rethink how you address me. We are far from finished.”
“Relax, I’m not as big of a bantha’s ass you take me for.” Boba rescinds his joke, a spark of trepidation blooming in his gut when he can see that Vader did not take too kindly to that gesture.
“On the contrary.” Vader argues, yanking Boba back towards him. “I know for a fact that you are.”
“Well, don’t blow a fuse.” Boba traces the frame of Vader’s life support panel, his own leather fingertips leaving traces of him all over the components. “I wouldn’t leave you like that.”
“I wouldn’t let you.” Vader towers over him, craning his head down to peer into the blackened T-visor.
“Mighty words for a man who just let me come all over his suit.” Boba straightens his stature, attempting to meet Vader at his height to no avail. Vader glances down at the mess, his rebreather hissing when he sighs at the revelation. With no facial features to gauge his mood, Vader’s body language communicates all Boba needs to know. “What? Are you going to tell me to get on my knees now?”
“I was contemplating that.” Vader’s helm tilts again at this admission.
“Then say it.” Boba proposes to him while stepping so close, their chests nearly touching.
“Careful.” Vader warns with an intentional dip of his helm. “It would be easier to kill you now without your pretty armor.”
“So, you like my armor, eh?” Boba only acknowledges the complement in Vader’s threat.
“I know a superior chassis when I see it.” Vader drags his leather-clad finger against the sharpened edge of Boba’s steel helmet and pushes it up by an inch to reveal his mouth. The shift obscures Boba’s sight as his visor is moved out of place from his eyes, forcing him to look down the bridge of his nose through the shade. “Beskar is a highly revered ore.”
“You still haven’t said it yet.” Boba lets his tongue venture out of his mouth at that last word and just barely licks the come off Vader’s finger. Boba’s flavor is salty and bitter, savoring it all the same. As they experiment with this, Vader staggers in his midst. One might believeVader is spared by these humane flaws, but the wits extend far past his very being and into the world around him. He is able to identify every scent that lingers in Boba’s sweat right down to the texture of his tongue when he tastes his glove. Boba keeps him on his toes by calling the shots this time no matter how much Vader may boast “I’m beginning to think you forgot what we were doing.”
“You do not give the orders here.” Vader quarrels to maintain his elevated standing, but Boba has a way of catching him off guard. “I do.”
“Then what are you waiting for?” Boba gives him another proverbial nudge and it strikes Vader deeply when he sees what’s happening. “Say it.”
“On your knees.” Vader disbands all mirth from his inflection, serious as he addresses Boba but these are the exact words he’s been dying to hear.
“As you wish, my Lord.” Boba obeys, playing along even though he has plans of mischief in store. He bends his left leg first, following with his right and Vader’s stature practically doubles as his perspective shifts. Boba winces under his helmet at the hard flooring colliding a little rough than intended with his knee guards, but will endure for this renown trophy.
Vader’s layers have not yet been uncovered, but that’s nothing a simple press of a button cannot cure. Boba’s eyes meet with the curved, silver buckle fit with a tiny triangular latch embedded within. With a steady hand and a dexterous execution, Vader’s entire utility belt, codpiece and all, meet the ground with a thud as well. His tabard is free flowing at each side, encapsulating Boba like a blanket all around.
Vader peers at him, their visors meeting once provoked by the steamy implications of their positions as Boba pushes the draping sections of Vader’s tabard out of his way. He is captivated by Boba’s resolve, respecting the bounty hunter for never showing even a glimmer of fear. Vader is known to harbor utter disdain for his own constituents, but when Boba’s success rate proved to be one of if not the highest in the guild, he felt obliged to get in touch.
“You’re a generous guy, you know.” Boba thinks to worm his way into Vader’s head, adding to the broiling rush of this engagement.
“I am no such thing.” Vader vehemently disagrees, his iron fist clinging to the notion that he is to be feared and feared alone.
“What you do is a thankless job, is it not?” Boba adds, playing his own mind tricks on him. “Has anyone ever shown their gratitude for how safe you keep the galaxy?”
“That is a subjective claim you would not be making right now if our rapport sang a different tune.” Vader bends down but only slightly, just enough to test his grip on Boba’s throat. He doesn’t squeeze or utilize his supernatural abilities, but to simply massage the muscle and admire his open collar. The warm tone of Boba’s skin travels from his clavicle to his exposed and moistened pubic wreath, a trail of hair rising up to reach his naval. “Moreover, my work is not merely an outlet for praise.”
“Then what are you doing here?” Boba asks, bypassing Vader’s closed trousers where he easily locates his stiffened cock, freeing it from the small and slitted opening. His inanimate elements are hidden by clothing, but Boba’s hands on his thighs identify where man meets machine.
“Enough chatter.” Vader’s hand moves from being clamped around Boba’s neck to pulling him forward by the jaw, his thumb and index finger pinching him at the hinge so his mouth stays open.
Boba smiles beneath his helmet when his widened mouth is invaded by Vader’s throbbing cock. The plump head sparkles with a sweet bead of forbidden nectar that Boba hastily licks up. The texture of Vader’s scorched and warped skin creates grooves and ridges that Boba didn’t notice the first time this happened. He was far too blinded by seething wrath that Vader would use him in such a way to even register the profound occasion. Even Boba didn’t know he had an appetite for the forbidden.
Vader maintains his hold on Boba’s jaw, moving him up and down his shaft to taste every inch of him until his nose collides with Vader’s structured torso. Boba slowly but surely demonstrates to Vader that he does not require his guidance. He takes initiative beyond Vader’s manual influence, evolving above the chaste up and down motions and acting with a bit of flair.
Boba gauges in his mouth how to better take all of him without gagging on it each time it hits the back of his throat. He tucks his chin, allowing Vader to fill his mouth and press staunchly into his tongue where he steers his cock to his hard palate. His jaw is opened to its furthest extents while he continues to bob while Vader’s audible breathing becomes more unstable by the second.
Vader lets go of Boba’s chin, giving over the reins to bolster his limbs so that he doesn’t buckle under the pressure. The cold, dead stare does a poor job of disguising Vader’s emotions. His modulated moans and gasps are peppered between the periodic hiss of his respirator, its motors kicked into overdrive to compensate for the exasperated activity.
Vader’s head is thrown back when Boba pulls his lips almost completely off his cock, circling the swollen and soaked tip with his tongue then practically choking himself right after. He intentionally goes down too fast, suffering the consequences with an inelegant gag.
Boba thinks it to be a mistake, committing to careful methods from here on out, but Vader will have none of it. He likes the sound, wanting to hear it again and again and again…
Vader rests his palms over Boba’s crown, keeping him still while he thrusts forward, fucking his mouth. Boba’s gagging becomes a percussive echo that Vader delights in, especially when he starts to grab fistfuls of his tabard and cape through the tussle.
Boba is starved for breath, needing to turn the tables and fast. He decidedly focuses on Vader’s weak points where his prosthetics join his corporeal form, pushing him as hard as he can until he loses his balance, falling backwards where he joins Boba on the floor.
Vader is saved by putting the heels of his palms out, catching himself before he could fall all the way on his back. Boba reigns supreme as he has Vader pinned now, his drooling and chapped mouth left agape and panting as he yanks his helmet back down. Vader curses him in his mind for taking away the precious sight, but his interests are piqued to see what Boba does next.
Once he realizes what this Dark Lord finds favor in, Boba is not as resistant to try new things, taking it by force if he has to since he knows Vader likes to play the game.
“Trying to catch me at a disadvantage, are you?” Vader says this as if he’s insulted that Boba would try something so debauched, meeting his fantasy with one of his own. “Very well.”
Vader snatches Boba by the collar, easing him into a straddle where his flight suit is torn apart. The opened section from his collar to his groin is breached beyond its bounds as Vader takes the fabric in his hands and shreds it so that Boba’s bare ass is put on display. His sleeves and pant legs are all that remain. Even then, the knee bracers are the only things holding what’s left of them up. Boba is jostled by the spontaneous wardrobe interference, tested more now than ever. “You owe me a new suit.”
“Whatever you require, you know the Empire will always provide.” Vader puts this discrepancy to bed, deciding to take Boba there next.
“Doesn’t matter.” Boba forces himself atop Vader, straddling his broadened waist and successfully pushing him down at the shoulders so that his back at last meets the floor. “It’s the principle of the destruction of property.”
“You’re my property.” Vader contradicts what Boba has to say with a rhetorical slander of his own. “To whom do I pay my dues for your destruction? Myself?”
“I’m no one’s property.” Boba disputes, gallant in his enunciation.
“You’re mine as long as you’re on my payroll.” Vader discloses, but Boba can read between the lines.
“Are you saying you’d be jealous if I took a contract from someone else?” Boba turns things around on him again, really getting under his armor this time.
Vader realizes the road this is going down, electing to punish Boba for these outbursts. There is no time wasted between Vader lifting Boba up and impaling him on his cock. He uses gravity to his advantage, pouring his essence into force fucking Boba. He doesn’t have to use hardly any tactile strength, relying all on his phantom grip to slam him down.
Boba loses all ability to enunciate another word as the impetuous fullness extends deep into his core. His ass stretches around Vader’s cock, the saliva smoothly easing it past his threshold through the stinging dilation. Though, just when Vader thinks he’s conquered his opponent, Boba defies his will with a plight that will not be impeded.
Boba embraces this position, grinding his ass into Vader and driving his cock farther than either of them anticipated. His hands are surrendered unto Boba’s grasp where he presses both into the dusasteel gorget over Vader’s chest. Just as Vader was impaling him with his upward thrusts, Boba collides his ass with Vader’s hips.
Boba’s cock tempts Vader as he fucks him, just flopping every which way right in front of his face. Sadly, He is not afforded the liberty of touching him, restrained and inhibited. Extensions of his frustration manifest in failed light sockets and sparks flying from random points in the ceiling. Wall panels are peeled off to reveal the inner workings of the building and the tiles under their feet are literally bending to Vader’s will.
Boba relishes in Vader’s defeat, a crater forming each time he seats himself atop this influx of inches. The sounds of destruction in the room grow more violent as Boba keeps at this, pestering Vader as the foundation of this building suffers. It is immaterial to them, worth far less than this moment. Boba raises the stakes by lifting a knee to allow for Vader to see all of him and in due course, he is subdued. It is not like Vader to wait on the grace of another, but with Boba, it happens all too naturally.
Boba reaches climax by his own doing, enhanced by the presence of Vader’s panoptic grasp. He releases a guttural moan when Vader feels his ass tighten around his cock, flexing in tandem with hot ropes being shot all over him for a second time. Boba’s cock bounces through every jutting release, extending the perimeter of the fast-accumulating mess.
It takes a bit more than this for Vader to get there, though he is not far behind. While still deep inside Boba, he scoops him up by that raised knee to shove him on his back and repeats the same with his other leg. Boba’s knees are almost pushed to his chest, the plates of his armor tapping against his helmet.
“Harder…” He begs with slight difficulty as Vader’s hands are occupied by keeping him folded in half. Boba does let another chance at rapture escape him. His gloves are saturated at this point, amplifying the slick grip he has on himself. Boba uses his other hand to assist in holding one of his knees back, spreading himself.
“What an… insolent act it is to make… demands in your position.” Vader enunciates gruffly as he drives himself into Boba, punctuating his words with his herculean thrusts. He pauses, draping his body weight over Boba to nearly flatten him, speaking directly into his ear. “I will now teach you that one who inquires soon perishes.”
Vader stays cascaded over Boba, his ample weight making it next to impossible to fuck his fist, but he adeptly realizes that this hindrance is actually his salvation. Boba has no choice but to graze his padded thumb over the tip of his cock as that is all the space Vader affords him. This scarce deliverance is made up for by the depth Vader exceeds, punching Boba assertively with his cock like a battering ram assaulting a spire.
Wheezes and hizzing resound from Vader’s helm where they pour into Boba’s ears, noises that no other living being would be caught dead hearing. Vader succumbs to the strenuous engagement and one of the hands locked into the crook of Boba’s knee comes crashing down beside Boba’s helmet. The steel rings against their skulls, coaxing them into an irreversible daze.
Vader is thwarted by the throes of passion, his unyielding slams and thrusts are met with an involuntary convulsion as pooling heat is deposited inside Boba. Their deep breaths join together in unison as the bliss of their synchronous release takes them by storm. Boba’s subtle stroking was not unfruitful, a third and notably smaller load being expended from his exhausted cock. His endurance has been all but depleted and his muscles are becoming aware of the repercussions of this venture.
Vader hovers above Boba for a few seconds, his cock still plunged deep inside as they study each other’s eyes beneath the esoteric screen. He gives him a couple parting thrusts, flexing his shaft to ensure every remnant has been gifted to his prodigious associate. They say nothing, letting their gasps tell all.
Vader gently slips out of Boba, bowing his head to see it exit by the inch, heaving a large groan when it slips out taking his pearlescent ooze with him. His cock swings so heavily, dangling between his thighs and running into Boba’s as he pushes himself to his feet. He intentionally leaves Boba on his back, admiring his used and vulnerable posture.
“I take it you’re leaving now that you got what you came for?” Boba asks, propping himself up on his elbows to see what Vader does next.
Vader is charmed by this assumption, closing in on Boba where he strives to do what he does best and unnerve him. His natural walk sounds like stomping, each stride booming through the floor. Vader takes a knee and with his cock still out, he reaches for Boba’s, overly spent and sensitive. Vader is lofty and mountainous as he dwarfs Boba, still lying on the floor.“I was hoping we’d talk contracts.”
Bottom darth vader x top boba fett? Pretty please ❤️
OF COURSE BECAUSE YOU SAID PLEASE!!! and just so you know, I have a prev ask for EXACTLY THIS from like the end of November(I can only assume it was also you...?) PLS FORGIVE ME I GOT IT AND IT IS HAPPENING AHHHHHHHHH!!! Life has been NUT as always It will be posted at some point this coming week, I PROMISE YOU Nonny!! Oh, bless your heart for waiting! I love you sm I hope it is worth the wait!!
In the meantime, have my tri-chapter series of exactly this while we wait for the next switcheroo installation where roles are reversed...🥴😜
Deploying this as a sticker on discord to haunt all my friends with my awful old men.
Fett has so many different colour placements on his armour and cape options I kind of just ended up slapping my own combination on it...
I wish I could credit the base but it's a meme that's been passed around for ages, I'll include it here though with the white background ver:
As an aroace fan, vaderfett are QPR coded to me, or at least I love it when they are.
Vader is a chronic pain sufferer and the suit is basically built into him. The parts that aren't are layered thickly and armoured. Even walking hurts - he cannot run or raise his arms above his head. So I enjoy headcanoning their relationship as less physical! Boba is willing to accomodate for Vader and doesn't have much interest in anyone else despite Vader's offers. And Vader kind of enjoys watching Boba do things solo jf he gets the urge. If/When it does get sexual, it's more about kink and exploration of dynamics than direct intercourse. Perhaps it isn't even sexual, just a sensory experience.
As for the 'romance,' they're both fairly emotionally stifled. Boba has a hardened shell to get him through a life spent mostly alone. Vader has had decades of emotional torture at the hands of the emperor. So I like the idea that they aren't necessarily romantically attracted to each other, or even capable of romantic attraction. I think there's something beautiful about two people sharing some of the same pains and deciding to intertwine their lives just to heal each other's wounds.
They don't expect anything from one another and that's perfect for two men who often don't have much to give.
Vader becoming so numb to the Empire's abuse he starts seeing himself as a droid.
Boba liking Vader in a droidfucker way.
Vader has lived 2 decades under the Emperor as his attack dog. He lives to serve, he knows his place. He does what he's asked and he doesn't expect reward - it's his only purpose. The rare times he's offered affection from his master are only to replenish his connection to the dark side, make him hurt again and again, keep him in agony both emotionally and physically. So why would he crave something more? He does his job well and he gets nothing for it and nothing is better than punishment disguised as reward. A life like that, combined with his suit and cybernetics make him more droid than person.
And Boba loves it. The wires pulling and twisting in his forearms as Vader examines his joints after a battle. The whirring of the gears in Vader's knees and ankles and the cold clunk of metal on metal as he struts the corridors of the death star. The synthetic breaths forcibly pumped through the last of Vader's anatomy as he struggles to bark his orders. Objectively there was nothing sexual about it, but Boba would argue he'd never seen something more arousing and he'd been in all the darkest corners of the galaxy.
The greatest part is Boba still sees the last shreds Vader's humanity. The unfiltered interest he takes in his ships and repairs and the repressed yearning for an unconditional connection of any kind that isn't masked as well as Vader hopes. He's fascinated by the way the cogs Vader's mind turn, the way he's so analytical of the world around him yet so blind to his own self. Boba has always been observant and how he has the opportunity to truly pick the man apart and put him back together.
It's the best of both worlds. The glinting body of a droid and the (somewhat) warm heart of a man.
