when you do the egg rebirth cycle you can potentially switch genders?

LOL, yes, actually I did see that get mentioned a few times in fic. Never actual kinkification tho'. But it's one of the biggest support for 二人论 camp.

joined the Quintet on their adventures (and it usually sounds like they had these adventures together as something of an elite spec ops unit

Actually am curious where this comes up. Is it in an item description, fictional recounts, or is this from an NPC? Because if it's part of the folk stories, then it's probably just story tellers having to make up stuff to make banal everyday drudgery exciting. If it's being relayed as a personal story, then there's more reason to believe this stuff was actually happening.

There's this one Vidyadhara dude who fell in love with the same Xianzhou lady for several lifetimes. The lady, on the other hand, went from thinking it's all quite romantic to have a boyfriend who still comes back after rebirth, to getting tired of it all and now rejects his advances (she's probably close to hitting her mara-limit, IMO).

I mean it probably got tiresome after the first two rounds, let's be real. But also this guy's cycle is either faster than normal or he's unlucky AF... (But also presumably this is the biggest hope for all the Dan Heng/Jing Yuan shippers.)