--He appears, directly in front of a woman walking quickly enough that she fails to stop before colliding with him and sending the both of them tumbling to the ground in a heap. 

She says something startled and apologetic in a language he doesn't understand. 

He cannot establish that he does not understand this because he collapses unconscious in a heap.

Random teleporting dudes are not normal! Or, at least, ones who don't have the discretion to teleport somewhere other than a public street. Ones who then collapse unconscious are just straight-up concerning. 

She checks to make sure he doesn't have any injuries such that moving him carelessly would be a bad idea, then scoops him up into a bridal carry and does some teleporting herself. 

When he wakes up, he will find himself alone in a room decorated impersonally in pale blues and heather-purples.

Apart from having a lot of blood on him - it's not his - he is unharmed.

He sits up and looks around and says, "Uh, hello?"

A moment later, the woman appears in the doorway. 

In his language, she says, "Hi! I've never heard of this language before, where're you from and where were you trying to go? I didn't find anything physically wrong with you, so I'm also not sure why you collapsed, are you going to do that again, should I be ready to catch you?"

"- hi! I don't expect to do it again, it can happen when a spell is almost but not quite right. If you tell me about how long I was out I can refine it for next time. I wasn't aiming for anywhere specific because I didn't know of anywhere specific to land. Uh, it's nice to meet you."

"Nice to meet you! I'm Lucy. You were out for about half an hour. I've never heard of spells having that as a failure mode. Are you from another universe or something?"

"If I was only out for half an hour then I think I can conclude that yes. That plus you being able to speak Senserke and claiming you've never heard it before."

"I have never heard it before! Welcome to Earth. Why were you trying to go to another universe?"

"My planet is being destroyed by out of control magical byproduct."

Her focus sharpens immediately; she straightens out of her half-slouch against the doorframe. "--Oh, that's not good. How fast? How long will it take you to be able to jump back--or teach someone else to--we can probably help, with evacuation if nothing else, if there's time to evacuate--"

"We think we have a few months before the place can't hold atmosphere. I can jump back, takes maybe fifteen minutes to draw out my spell diagram, but I can't teach people here, requires access to a magical byproduct location. Also every time I do the spell it makes it worse. A place to evacuate to is good but before we scale that up it may be more important to find a planet we can breathe on but that nobody's using."

"Okay. How much does doing the spell accelerate byproduct buildup? Is the spell guaranteed to land you somewhere with atmosphere? It might be more efficient to terraform a planet in this universe than to try to find one in another one that's already habitable, I am confident in my ability to terraform a planet one way or another but it hasn't been a priority yet so I don't have a good estimate on how long it'll take, but if I call in enough favors it should be doable in less than two months I think. What's your planet's population?"

"Bit under a billion - you can terraform a planet?"

"I'm very magic. But doing it myself might not be the best idea, the fairies have been working on the project of interplanetary colonization for years. They haven't done any yet but there's this neat dome habitat somewhere very inhospitable on this planet. This planet ish. Recreating their project to create an adjacent pocket dimension with a duplicate of this planet on it miiiiiight be faster, if it can be done."

"I was not expecting this spell to work at all, let alone this well, wow."

"You got very lucky landing on me! Uh, also, probably shouldn't surprise you with this only after we've sunk a ton of costs, this universe has an afterlife situation." 

"That... sounds better than the alternative, is it?"

"I wouldn't trade it in. But, uh, it is not perfect. There are two afterlives, and one of them catches the overwhelming majority of people, and the other one catches one every couple of years and is, uh. It is, strictly speaking, my reason for existence to solve it."

"...that's a strictly speaking?"

"I mean, I'm not going to stop solving problems when that one's dealt with."

"I mean, more, how is it the reason for your existence."

"Oh! Remember how I said I was extra magic? We have a God. She set up the main afterlife on purpose and the other one not on purpose. She managed to empty it out a couple thousand years ago but she made me to fix it for real. She found a," she waves a hand, "a place, sort of, that had--patterns, stories and people, that happen over and over again in different universes. That's how I knew other universes would exist. She found my pattern and decided I would be good at it. So she made me."

"O....kay. Nice work if you can get it. Uh, what do you need from me to get on the terraforming thing - we ideally want separate planets, here, one to put refugees on since it'd be a lot to dump on an inhabited planet and one to put more magical byproduct on."

"Does the byproduct one need to be habitable all over?"