Had these three done forever just forgot to post them oops— anyway, here are The Specs!
TLDR lust (or doc) is a mad scientist that when crazy trying to learn about the multiverse, and decided to summon a demon. That demon being fresh! They eventually struck a deal and began working together. Grease was some sucker they kidnapped for testing, but he ended up being so into it that they just kept him around as doc’s new assistant, the call him “lab rat” as a nickname.
Anyway they’re polyamorous in a very Adam’s family way where they are very very evil but have a perfect healthy romantic relationship
OK, I liked writing the last one so much I wrote another dumb little mirrorverse fic. This one’s a bit spicier than the other, but nothing that goes against Tumblr terms of service. again, sorry for any typos
Romantic relationship: fresh x greaser x lust
CW: arousal, possession, loss of control, and of course: 
(sorry I’ve been wanting to use that gift forever)
Anyways, here it is

You’re enjoying this a bit much, aren’t you?
The doctor taped his pen against his clipboard. Unsure of what to do. “Hey baby doll~ need somethin?” Called his lab assistant. Greaser sans was tall compared to the doctor, yet he and his other partner still called him— “ah, Lab Rat… yes I am in need of something”
“What can I help ya with?” He said, sitting down backwards on a near by chair. Leaning against it’s headboard. “I don’t have enough data on fresh’s possession ability to form a proper hypothesis for this particular scenario…” he rubbed his chin, before glancing to his assistant and looking him up and down. A devious grin growing on his face “But… I know where I can get some~”
The doctor called fresh into the testing chambers, before telling him and rat of his plans…
“You w-want him to posses… me??” Greater stammered “precisely~” replied doc. “With you as a willing participant, I could collect much more data before separation. And you and fresh could spend some… quality time, together~” greaser’s blue blush flared as fresh put a hand on his shoulder. “Chillax broski! It’ll be rad!”
Fresh stretched his arms above his head. “So when do we do we start?” The doctor began taking notes “whenever you’re both ready~” fresh smiled and looked over to rat, cupping his face in one hand. His other hand slid down his own throat, pulling up a single writhing purple parasite. Fresh held in over the other’s face, as to drop it in his mouth. “Open wide~” he cooed.
Grease was shaking in his boots. His normal witty banter falling completely silent as he looked up at the parasite above him. Fresh’s face went from satisfied to concerned and contemplative. Before he let go of rat’s face and dropped the parasite on the floor. The purple star crawling back in through Fresh’s pant leg “this don’t feel right… “ he said, tapping his foot. “Heya doc!” He called “yes fresh?” The doctor replied
“Would it mess up yo research if I was the one to get in there?” Questioned the colony. “and… What do you mean by that?” Fresh looked to rat and bent down to meet their eyes. Staring deep into their soul. “I want in there… no arms. Me.” The authority in Fresh’s voice sent a shiver of anticipation through greaser. Doc taped his pen to his chin. Before a look of realization bloomed on his face “you… want to posses him with your core instead of one of your arms…?”
“Bingo!” Fresh replied. Complete with finger guns.
“You’ve never shown interest in something like that before…” replied doc. “Heh, yeah…” fresh cupped greasers face with his hand again. “Never had someone interest me like this till now…” at this point, greasers entire face is glowing bright blue. Causing doc to chuckle at the site. He gave a warm smile to his partners, happy to see them so infatuated with each other. “Yes fresh… this will affect my research. But seeing as you also have an interest in this Avenue, I believe it will be valuable nonetheless. So we shall proceed.”
Fresh pumped his fist in the air and moved to the center of the room. He spread his arms wide and took a deep breath, before his body seemed to disintegrate, leaving a pile of parasites where he once stood. The parasites crawled away into the containers lining the walls built just for them. Eventually, all that was left, lying on the floor, was the biggest parasite.
The creature’s eye soon snapped open, zeroed in on greaser. “T-thats still him..?” Rat managed to choke out. “Yes. That is the hive’s core. Think of it as a queen bee. It’s the glue that holds the rest of the colony together.” The doctor replied. Rat looked between fresh and doc before stammering “w-what now?” Doc chuckled under his breath “simply approach whenever you are ready~”
Greaser looked to the floor, slowly creeping towards the parasite. “H-hey doll… it’s me! You can see me.. r-right?” But before he could form another thought, the star leaped at rat’s face, knocking him onto is back.
Greaser grabbed at fresh, rolling around like he was on fire. “Let him in, sweetheart~ I can’t do any testing if you resist~” doc reminded him. Rat remembered the thing on his face was his friend, his partner, and tried to relax. The parasite weaseled its way into his mouth, and down his non-existent throat. Causing the other to choke and gag.
In an instant, greaser felt as if he was being embraced on all sides. Every part of him held close, as fresh wrapped himself around rat’s soul. Grease began to quiver, eye lights going wide under his sunglasses. Pure euphoria coursed through his veins as what felt like a kiss was pressed into his very being. Rat let out a small wine as fresh took over. A puff of rainbow smoke engulfing his body.
Greaser awoke in is own mind. It felt as if he was floating in a void. He could see through is eyes, but he couldn’t move. couldn’t speak. Yet he felt so… safe. It still felt as if he was being hugged form all angles. An embrace so close that two became one. Loosing control… it felt… good. Less like a forceful eviction, and more Like his partner gently pulling him to the side, kissing him, and saying “don’t worry my love. I’ll take it from here.”
Rat relaxed in is mind scape. Metaphysical eyes rolling back in his head as he soked in fresh’s intent
Your mine/can’t escape/part of the swarm/part of me
Doc coughed on the smoke, waving his hand in front of his face. As greaser stood, the smoke cleared. Reviling his new appearance. The possessed rat shot the doctor a pair of finger guns“Hey-o baby! How’s ma favorite doc doin?” The doctor chuckled at Fresh’s advance. “Doing wonderfully sweat heart~ how do you feel?”
“Radder then eva broski!” And the doctor could tell. As sparks of magic, usually reserved for if monsters showed affection (hugging, kissing, purring), were shooting off greaser’s body at an almost alarming rate. As if his test subject’s entire existence as an act of love. And it was.
“Alright you two… it’s time to get to work~” doc said with a mischievous grin. The doctor ran a full physical on the fused pair. Along side some strength and magic tests. In all It took just about two hours to collect all the data doc wanted.
Greaser sat on an examination table as doc jotted down some final notes. “Now then… that is more then enough for today. Boys…” doc glanced to fresh and rat, before pausing. Examining the two. Fresh rubbed grease’s thighs together impatiently. Their ecto drenched in sweat. And the way they looked- no- stared at him. Even through their glasses, it was a look lust knew well. “My my~” he began “you two are enjoying this quiet a bit… aren’t you~”
Greaser screamed out from within his mind. YES. GOD YES. He was enjoying every moment of this connection more than anything he ever had before. The feeling of being engulfed in someone else’s intent. The feeling of fresh gently moving his body for him. It felt like he was in heaven. Fresh was enjoying this too. The feeling of power, of control… but most tantalizing, trust. Greaser truly trusted him with his body. A sensation fresh rarely if ever felt from his hosts. The words spilled from their mouth as they were lost in each other. “Absolutely~”
Doc’s smile grew as he stepped forward, placing a hand on their partners face. His thumb rubbed their cheek. “Well then… I believe another type of testing is in order… wouldn’t you say~” both fresh a greaser salivated at the idea “Of corse!!” They blurted out.
Lust backed away, setting down his clipboard. His voice was silken and sweet “Follow me~” he said. Gesturing towards the door. Fresh and greaser hoped off the table and ran after the doctor. Lust slipping off his lab coat and hanging it up as they left. After exiting the laboratory, they moved into their shared bedroom at the end of the hall.
They had the whole night to themselves. And they were gonna make it count.
…
Later that night, the pair were cuddling in bed. Fresh felt a tad worried about how long he’d stayed in his friend’s body, and began to crawl out through their mouth. Only for grease to slap and hand over fresh’s exit. Keeping him inside. The parasite was confused. Before tasting the intent behind the action
I’m yours/stay with me/part of the swarm/part of you
Fresh paused for a moment. Realizing that, never in his vast lifetime had someone with for him to stay with them. Be part of them. Fresh’s tentacles wrapped back around the other’s delicate soul. Cradling it as if it was his whole world. A small sound escaped rat’s mouth as he began to purr of his own fruition. fresh snuggled tighter as grease began to drift to sleep
The next morning, rat was disappointed to find himself back to normal. Only to fluster at the realization that fresh was back to his normal self as well. But not only that, he was also in bed with them, snuggled against greaser’s back. As lust held him from the front, grease was trapped in the middle of a cuddle pile. And he couldn’t be happier. Smiling, purring, and deciding that waking up could wait a little longer.
