Rose sighed. Today had definitely been something of an emotional rollercoaster. When she had awakened, it had been in this overheating, starless universe, to which she had never expected to return. About last on the list of things Rose expected to happen today of all days was what was going on right now: sitting comfortably next to a human version of the Doctor with her mother looking on placidly, as though they hadn't almost died just a short time ago.
An exhausted, sorrowful sort of relief was evident in the Doctor's face, and Rose forgot for a minute that this Doctor was human. For the first time since their passionate moment on the beach, perhaps half an hour ago now, Rose felt guilt prickling at her skin as she thought about the Time Lord who had left in the TARDIS. However much he had encouraged her to accept the Doctor who now sat next to her, and however sweet the human Doctor's whispered words had sounded in her aching ears, it occurred to Rose that she had likely carelessly broken both his hearts by not restraining herself until after the Time Lord she loved had gone.
As a result, a barely tangible yet very distinct feeling of mourning descended upon her, and Rose found after maybe five minutes of staring into space that she had unconsciously decided that in the memory of the Time Lord she had lost, she would take her time with her relationship with his human incarnation. They had all the time in the world, after all.
Suddenly, an unwelcome thought invaded her mind that directly contrasted with her newfound resolution: it had almost been a dying wish for Rose to take in the human Doctor, and at this startling revelation—that the Doctor with two hearts was as good as dead to her—Rose felt her eyes well up with fresh tears. Perhaps to stifle her smothering loneliness, or perhaps to rebel against her regretful decision to take things slowly, she not-so-gently pulled the human Doctor's head into her lap (he yelped in surprise), struggling to keep herself from overflowing again.
After his initial surprise, the Doctor lay quite still, staring up at the bus ceiling with an unreadable expression: this was the only time he ever truly looked his age to Rose. She could tell he was not seeing the roof. He was seeing the stars he could no longer visit in person, grieving for the TARDIS he would never see again. Rose clumsily laid her hand on his single heartbeat, accidentally startling him out of his thoughts, and a single tear dropped onto his cheek.
Rose embarrassedly wiped off the drop of saltwater with a muttered apology; the Doctor's only response was first to brush her cheek tenderly, and then—to her astonishment—to allow himself to cry as well. For the people and things they had both lost, for the stars, for the lives they had taken, for a future they had now prevented, and—most of all—sheer, delayed relief that they were alive, and alive together.
Hopefully, forever.
((Darker than the rest, I believe, so I'm doing another chapter without any waiting at all, just to show a bit more of what this is about…))