Well, I didn't mean Doctor Medico wasn't welcome right now, but I will accept the canon Sentinel Comics universe answer that every character but Doctor Medico is welcome at my house! ;)
I think the answer about Tachyon running faster than light was surprisingly beautiful - in-universe, she shouldn't be able to do that, and she knows that, and that's one of the questions that dogs her studies. Very cool!
So now we know that every character in Prime War either comes from a destroyed universe, or was lost in time and space (or similar). I get the impression that this is connected to C&A's insistence that the characters who left Universe One via a Mist Portal didn't necessarily make it back home. So it's possible that the Inversiverse is gone (since Black Frost is displaced), but Princess Luminary is still out there somewhere. Same goes for Supply & Demand Benchmark. There's also the Ahoraverse (Night Terror and Disparation Dark Watch), and I don't think we know what universe Windwalker is from.
First appearance of Nimbus, my favorite other letter writer, even though believe he wrote an earlier level with a different name and the later tagline “Lord of the Heavens, Master of the Wind and Sky”. When the name and tagline combine, they become such a cool character byline that I wish there was an actual deck for it.
Christopher and Adam and Cody and AJ and Ryan reading letters to you. Doesn’t have quite the same ring to it.