Request/Summary: With the Not-Things, there's a lot of potential for angst and hurt/comfort, etc. Totally fine if you don't want to write this, but I keep imagining a reader companion who has been secretly pining for the doctor and the Not-Thing reveals their love for the Doctor while trying to prove itself and yeah
Wild Blue Yonder Spoilers.
"You don't fool me," The Doctor says bluntly, looking at Y/n with his arms crossed and a grimace on his face. "You're not them, and I'd strongly suggest you stop pretending to be so before this ends badly." He threatens, voice dropped low into an hair-raising whisper.
"But I am! I'm me." They try quickly, tenuous pout on their lips and eyes full of tears. They place a hand to their heart, expression morphed into one of desperation. "Please, I swear! You have to believe me. After everything we've been through, you've got to know that it's me."
Scoffing and standing tall, eyes darkening dangerously, The Doctor shakes his head immediately. "Don't." He spits, taking a step forwards, so brutally it causes Y/n to step back in fear. "Don't you dare."
With eyes ingenuous and lips parted to allow shallow breaths to escape, Y/n responded quietly. "If I'm not me, then how would I know everything I do? How would I remember standing on the edge of civilisations, watching planets burn and being able to do nothing to help. Evil monsters - the ones that gave me this scar, remember?" They struggled, running a trembling finger down the little scar on their neck.
His face remains unimpressed. Blank. Angry.
"And how would I know how in love with you I am?" They whisper, swallowing thickly. "That thing may be able to fake being me, but they would never be able to fake a feeling as strong as that. Never."
It's silent for a moment, but then The Doctor's already dark manner growed into an appearance edging on detrimental. Without fear, he marched towards them, grabbing them harshly and restricting their movement.
A shriek left their lips, panting as they fought to escape his tightening arms. But then, their body fell limp, and they turned their head to look up at the doctor, smirk rising on the corner of their lips. "Got me." They taunt viciously then hissed as they kicked a way out of his grip.
Travelling with the Doctor, Y/n had grown accustomed to fear. The way blood would pump faster, the heart would bang harshly against the chest. It felt like it was going to burst out.
A few feet in front, the Doctor and Donna found sanctuary in the tardis. Unfortunately, Y/n was a tad slower. The two of them, Y/n and not!Y/n, exchanged a look before rushing into a full blown sprint.
"it's me!" Not!Y/n yelled as they ran. Arm reaching out, harsh breaths leaving their lips. "I'm me!"
"No, they're not! I'm me!" They corrected before suddenly halting in their sprint, hitting the other's back as they face the Doctor in the tardis.
But the Doctor's eyes never once glanced at the clone. Always, they remained on Y/n.
"I-I don't know how to prove it.." Y/n trailed off quietly before groaning, running a hand down their face. "Oh, gosh! Why can't I think of how to prove I'm me?"
"You don't have to." He answered simply, grabbing their hand and tugging them into the tardis, the doors immediately snapping shut with a bang.
"No!" Not!Y/n screeched as the door closed. They hissed and growled viciously, snarling at the fading spaceship. In a futile attempt to get the ship to stay in place, their nails clawed pathetically at the wooden box, blue chipping off and dirtying under their fingernails. "No!"
"That was scary." Y/n began, walking into the console room, freshly showered and in pyjamas, hair damp and eyes tired from the day's events. This captured the Doctor's attention and he immediately looks up from fiddling with buttons and such, a tiny smile instantly forming on his red tinted lips. His cheeks turn a sweet shade of pink at the sight of Y/n in one of his old tops. "I mean, I was starting to doubt that I was even the real me. How can you be so sure that you know I am?"
"I know," He assures quickly, not missing a beat. "and I will always know."
Blinking swiftly and nibbling their lip, Y/n looks down to avoid his eyes as their own cheeks colour, heart beating promptly. "Oh."
"You know," He begins, deserting the button he had been messing around with. "the other you said something interesting."
"Oh? Really? And what was that?" Y/n mumbles softly, rubbing their sleepy eyes and letting out a yawn. Upon seeing this, the Doctor's eyes soften and he grins, walking over to them and cupping their cheeks in his hands.
"Doesn't matter." He responds in a gentle voice, leaning down to press his lips delicately to their forehead. "Go get some sleep, angel. We can talk tomorrow."
As always, not proofread cos I'm lazy 🙈