"Another alt of Miles, who inconveniently was five and embarrassingly had an adopted sister who was my alt, came from a universe similar to ours but with magic. We have acquired textbooks on it. Elcenia also has a lot of magic, although accessibility is awkward given the situation with the door - I do get the impression that you could get a fair amount done with it as long as none of it needed to be performed or sustained outside of Elcenia, though."
"There must be some way to—right, I'm sorry, but it has to be done," says Mark. And he puts on Miles.
The actual Miles looks pained but doesn't voice an objection.
"So," says Mark, reverting to his standard self, "you can stop acting like we might try to kill you at any moment."
"...Why would we kill her? Who even does that, kills random girls from other universes who stumble into bars?"
"Has she been acting like that?" says Miles, somewhat disquieted.
"As though deep in enemy territory with next to nothing in the way of allies," says Mark.
"...Wait, if that's so, then how... do you..." Stalas waves his hands vaguely.
"Are you doing a convincing Solvei impression based solely on historical records? If you haven't met I assume the solution to the puzzle isn't 'you're immortal for some reason'..."
"I believe I've mentioned objecting to that interpretation," says Solvei.
"Perhaps you could explain just what it is you object to," says Mark.
"I'm not a 'convincing Solvei impression' any more than you're a convincing Mark impression."
"I've been informed I'm not welcome in the Miles club, even under corresponding conditions."
"...So... your assertion is that you currently are Solvei, foundationally, in a way that I am not correspondingly Miles when I am Miles?"
"Yes. There is a fake Solvei available at this address, but I am not she."