Yes. No. Maybe. I don't know. Can you repeat the question?

Poseidon just sees Annabeth and gets MAJOR flashbacks to Six Hundred Strike.

I personally only use this head canon when I need them to be on their 3rd life (with Perseus and Andromeda being the other life). While it's really funny for Percy to be Odysseus, I also prefer them with Annabeth as Odysseus and Percy as Penelope. Like you said, it just make a lot more sense. She just fits Odysseus's personality and backstory so much better than Percy. Plus betrayal by a long term friend who's basically a sibling to you? Check. And by the end of PJO, she's got the whole "I understand you're all gods and could kill me in one second but do know I hate all of you" (plus with HOO she got her beef with Hera to match with Poseidon's lmao)

Penelope's caring and loyal nature does fit with Percy. And if we want to get sad, it also fits with his childhood of a hostile man living in his home despite his wishes. I think he'd get deja vu during his childhood, except with a sort of off feeling as he's now in Telemachus's place. Also Poseidon being overprotective because "yes I know you two are soulmates, but like just this ONCE can't you not." It does not help that Annabeth/Odysseus's recklessness seemed to have rubbed off on him as he's throwing himself in every danger

Who's gonna win, one sea god or one glaring girl with her boyfriend (who is also the god's son) making baby seal eyes up at him. Spoiler, it's the couple. Anyway, there's totally a moment where Poseidon realized they reincarnated after they're clearly crushing on each other. Then he turns to Athena just in time to see her smirk and look away

yes you may!!! i’m going through my request right now so anyone can send them :P AU requests might be the easiest inspiration wise so plsplspls send me those pf any character ever