Author's Notes: Set very shortly after 'Journey's End'. Warning listed at the end of the fic.
So this was what dying felt like.
The Doctor's gasps seemed to echo around the darkened bedroom he'd been shown to for the night as he clutched alternately at his bed sheets and at his chest.
Some terrified part of his mind was aware that there would be no more regeneration or respiratory bypass or any of the other failsafes on which he was so used to relying. All he had to his name now were these underperforming organs and dulled senses. He was already mildly lightheaded and soon to be experiencing much worse purely because his body just wasn't able to do enough.
His lungs were filling with air without incident, as far as he could tell, but that single heart of his was too weak, too inefficient to keep up. He was suffocating in a room full of perfectly good oxygen.
What a useless way to go.
He flailed, panicked, and nearly thrashed his way entirely off the bed until two hands came to rest securely on his shoulders and more or less pinned him in place.
"Doctor," an urgent voice said. The weight of another body settled on the patch of mattress beside him. "Doctor, stop it. Just breathe normally."
Even in an unfamiliar setting and with minimal light to hand, and even after years spent separated until today, the Doctor would always instantly recognise Rose Tyler. And he'd certainly always want to accommodate her. But he simply couldn't. Not this time. This less than entirely familiar body seemed to have a mind of its own.
"If you don't breathe slowly you're gonna pass out," she warned.
Pass out? He was dying, thanks very much.
"My heart..." he choked out.
Sounding nowhere near as alarmed or, failing that, at least sympathetic as the Doctor felt was warranted, Rose said, "Hey. Look at me. There's nothin' wrong with your heart, except that it's beatin' a bit too fast right now."
That was all well and good for Rose to say. It wasn't her vision that was whiting out, or her chest that felt as if it was on the verge of exploding.
Regardless of the fact that the Doctor felt like he was in a far better position to understand his malady, Rose apparently decided that the onus was on her to determine precisely how he should be treated. She chose that moment to test out a proactive and creative way to stop him from hyperventilating.
Her lips closed over his, and he forgot to breathe altogether for several moments. Then, since he suddenly had better things to actively concentrate on, his instincts took over from his conscious mind and his breathing started slowly normalising, with his heart rate decreasing incrementally along with it. He didn't even notice that he was taking long inhalations through his nose by the time Rose fully opened her mouth against his and darted her tongue out invitingly.
Finally, Rose pulled away just far enough that her own breath still warmed his cheek.
"Better?" she asked.
It would be 'better' if she was still kissing him, actually, but he nodded all the same.
He'd always been impressed with Rose, but he really thought she should have mentioned that her kisses had such miraculous powers of healing sooner. It could have been extremely useful.
Not that he would have wanted to see her demonstrate her skills on anyone else, obviously.
Rose didn't seem to think she'd done anything particularly outstanding, though. She said without fanfare, "You were havin' a panic attack. You just needed to calm down and stop pantin' like a dog, is all."
A panic attack?
Seriously. A panic attack?
Well. Time Lords never went about taxing their systems over a little bit of post-metacrisis anxiety, let alone making the mistake (in front of an audience, no less) of thinking they were actually dying of it. Stupid fragile new body. He might yet end up expiring of embarrassment rather than asphyxia.
Being half-human, the Doctor decided, was rubbish.
Rose smiled at the Doctor, and his heart started thumping a little harder once more.
Actually, considering the kinds of perks that seemed to come along with it, maybe being half-human wasn't so terrible.
"What caused all that, anyway?" Rose asked. "Did you have a nightmare or somethin'?"
"Couldn't sleep at all, actually," he said. "I kept hearing the sound of my heartbeat, and I couldn't stop thinking about how much blood has to circulate my body just to keep me alive and how one heart can't possibly do all that work and if this heart stops there's nothing to stop me from –"
"Woah there, careful you don't set yourself off again." Rose stroked her thumb lightly over his lips as if to silence him. "I always did wonder whether one day you might think yourself to death, but I have no intention of lettin' you die on me any time soon. Humans have been doin' just fine with only one heart for ages – which, by the way, you should know better than anyone, havin' actually been back in time to see us crawlin' out of the primordial soup or whatever."
Right. He did actually know all that, of course. He blamed the newly-human bits of him for his momentary lapse in logic.
Though, admittedly, the Time Lord parts were probably responsible for his tendency to overthink things, and this regeneration had never done well with the kind of silence or seclusion he'd encountered in this bedroom he'd been relegated to.
"It's too quiet all alone in this room. Might be better all-around if I just skip trying to sleep tonight," he mused aloud.
"Or..." Rose started, but she sounded hesitant to continue. He caught a brief flash of teeth as she worried her lip before suggesting, "Or maybe I could stay with you instead. I mean, you must be tired after everythin'. Probably best to at least try to get some rest. Though only if you want, of course," she was quick to add. "Up to you."
He wanted. Oh, how he wanted. He would have begged to share a room with Rose from the outset if he hadn't worried that moving that quickly now after taking years just to admit aloud that he loved her would send her running.
Despite his eagerness, he almost managed a casual tone while saying, "That might be beneficial."
Now that his higher reasoning abilities seemed to have returned to him, the Doctor knew it would actually be a better idea to follow Rose back to her room, where the bed was at least large enough to properly accommodate two adults. However, Rose was already curling up tightly against his body, and the Doctor wasn't feeling particularly moved to break that contact any time soon.
Rose's head rested on his chest, rising and falling slightly with each of his now-steady breaths. Perhaps lulled by that movement, or perhaps exhausted by jumping between universes over and over for however long, she was quick to drop off to sleep.
The Doctor doubted he himself would be getting any more sleep than he would have had he remained in isolation, but he was more than all right with that now. This way, no matter how long he was lying there in the near-quiet room – Rose broke the silence by kind of wheezing a little as she slept, he quickly found out – he knew he wouldn't be driven into a panic again. He had better things to think about now than the limitations of the human cardiovascular system. He certainly had no desire to think about dying.
Staring down fondly at the top of Rose's head and feeling her fingers grasp reflexively at the material of his shirt, insomnia actually started to seem like a sort of enticing prospect.
For he'd lie there and watch her sleep forever if he could.
Warning: Deals with the concept of prospective death (sort of) in a vaguely humorous way. Please avoid this fic like the plague if that's problematic for you.