Something that caught my eye:

“Arthur,” said Oberlin, pointing at Reimer.

Reimer blinked for a second, but didn’t correct the instructor. Not that Arthur wasn’t his name, but that wasn’t how he introduced himself, and no one back in Bumblefuck had called him that (and I was guessing that the same was true for Fumblebuck Reimer).

I don't know how I didn't notice that his name was Arthur a few chapters back (although I'm not surprised I totally missed it back in Speculation & Scrutiny).

There's nothing in the text that points to the Reimer on Earth only calling himself by his last name because he grew up as with another Arthur as a close friend... But if that is the case, it's interesting that he still goes as "Reimer" on Aerb.

There's another Maddie, despite the existence of Raven; maybe there's another Arthur, despite the existence of Uther.