It’s something that she wished she would have picked up on sooner, but is just glad she’s discovered it now.
This version of him always kept the TARDIS warmer than normal, warm enough to cause Clara to strip off her own layers to keep from sweating through them. It wasn’t, however, something she had actually thought about too deeply. Until now.
“That’s why you keep the temperature so high! Hah! Honestly, I think this is one of the best days of my life. ‘Superior Time Lord biology’ my arse.”
She can feel his frown against her skin, but despite his annoyance he burrows closer to her.
“Shut up.” He mumbles against her neck.
He’s lying practically on top of her, face pressed in the juncture of her shoulder and neck, her arms wrapped around him. The duvet is covering them and despite that, the warmth of the room, and Clara’s own body heat, he was still shivering against her.
“God, it’s like 30 degrees in here how are you still cold?”
“I don’t know. It’s just a thing with this regeneration. I’m always cold. It’s quite a nuisance, really.”
She glances around the room at their clothes scattered everywhere, noting how many more he had than she did.
“The layers.” She says. “That’s why you wear so many layers all the time?”
He nods and nuzzles her neck, absentmindedly pressing a kiss there.
“Surprised you never noticed before.” He says it softly, sleepily and she can feel that he’s stopped shivering. No more goosebumps either.
“You warm enough?” She may give him a hard time for it, but really she’s glad for it. Not only is it completely adorable, but it makes him seem more vulnerable, at least to her.
He nods again. “Perfect. You make a great heater, Clara. You should look into doing it full time.”
She grins and presses a kiss to his hair, shifting until they’re both in a comfortable position. He sighs softly against her, already half asleep and she whispers to him.
“Goodnight, my Doctor.”