Just a quick little thing I wrote on the spur of the moment on Tumblr in response to fanart of Loki and the Tenth Doctor. For what it's worth, this was written pre-Avengers; I suspect the Loki we actually saw there would've been a lot less likely to take the Doctor up on his offer than the Loki we got at the end of Thor, but hey, maybe this could've happened just when Loki's scheming started to involve Earth.

"Look, here's the thing—I get it, I really do, you've had a rough go of it, and the exile business, not belonging with your own family? Not much worse. So that's why I'm telling you this now, one pretty infamous trickster to another: you get one warning, and this is it. Call this off and leave Earth in peace, or I will stop you."

"…I almost wish you would."

"Then stop. Turn back now while you've got the chance. I'm not the only one defending this planet either, you know."

"Don't you dare tell me to go home."

"Wasn't planning to. I told you, I'm well-acquainted with the whole exile business. I mean, it's worse when your home is actually, literally gone and you couldn't go back if you wanted to, but, you know. The alternative is bad enough."

"Then what, exactly, do you propose I do?"

"You know what? Come with me."

"…what?"

"Sorry, was that a rhetorical question? I'm never good with those. No, I'm actually serious. Come with me. The Bifrost is all well and good but if you restrict yourself to that and Yggdrasil it's awfully limited, is the thing, and the fact is there's way more to the universe than even you know. Also, the TARDIS can go to any time, and that's a trick you can't do with your rainbow bridge up there."

"I'm trying to decide if I should take this as a compliment that you think I'm dangerous enough to need…babysitting."

"Oh, please, that's not—okay, that's a little it. Not much. Just a little. Bit of a two-birds-one-stone thing. The main point is, the universe is mad and wonderful and terrifying and big, and you haven't seen a fraction of it. Do you good to see a little more, in a lot more ways than one, and I could use a brain like yours on the TARDIS. Who knows, you might even decide mortals aren't so worthless after all. Short-lived and sometimes insane, but brilliant too."

"Well. As I believe these particular mortals say…what the hell."

"Indeed. Allons-y, Loki—ooh. Surname. Tricky. Don't suppose you've quite settled on one."

"For now…just Loki."

"Right then, just Loki, allons-y, you've got a whole universe to meet!"