It was a pleasant evening. He showed her around his childhood home (much like the TARDIS, it was larger on the inside), they had tea, and he eventually sent her off to her own bedroom. He considered kissing her good-night but opted against it. It would feel too much like goodbye.
He didn't sleep, of course. Too much to do and all that. By the time he slipped away from the house, one of the twin suns was just starting to touch the horizon.
In a pile on the kitchen table is a crude tattooing kit and a copy of the pentagram that Sam had shown him, along with some mechanical odds and ends showing only that the Doctor was working on something.
On the main table, however, is an oddly-shaped key, a card, and a silver disc. When pressed, the silver disc transmits a holographic image of the Doctor, recorded the night before. He looks rumpled and very tired.
"Hello, Rose. No doubt you're probably positively furious at me, am I right? Shouting at this holographic image isn't going to do you any good, I can't possibly hear you, so don't waste your breath. Still, a promise is a promise and I did promise Sam and Dean that I would help so off I'm going back to Earth. But not you. No, you're staying here, where it's safe. I promised Jackie I'd take care of you and yes, yes, she's in another universe but if anyone could reach across universes and slap me, it's Jackie Tyler so I'm not risking it."
Clearly agitated, the holographic image of the Doctor scratches its head.
"Right! Right, things I've left you. Left you the key to this house, though I don't imagine you'll be here for more than a few days at the most, and a card with some credit units on it. Don't spend it all on sweets and don't try to sound some sort of alarm, you have to keep a low profile, do you understand? Even if you're blindingly furious at me, don't waste your chance to live. Please, Rose."
The holographic image sighs.
"The TARDIS is programmed to come back here to get you upon my death. If something happens to me, I'm not going to just leave you on a strange planet. The TARDIS will arrive, it'll pick you up and take you anywhere you want to go. Now, I'm not going to try to die, I'll do my verybest to stay alive. But just in case, you know you're taken care of. I know you're taken care of."
He takes a breath and chews on his cheek.
"There are so many places I want to take you. Things I want to…if something happens to me, I'll regenerate and probably be just fine. Or at the very least I'll be terribly heroic and create some sort of mythology, am I right? If something happens to you, Rose…I won't let anything happen to you."
It's as probably close to 'I love you' as he can get.
"So. Be safe." He grins rather stupidly. "Wish me luck."
The image fizzles out.