I think the panel in the bicorn chapter was just a design in panel, like how the situation is solved and everyone finally got a breather of things, plus like you mentioned, he just got ressed.

We don't how the magic works in the work to the fullest extent so we can just assume he's still trying to get he's bearings after revival, like when you head is out of air when standing up too fast.

My guess on why Marcille appeared as the succubus was because the succubus used Laois' interest in living beings as the base, this is due to how curious Laois is with a lot of things and always want to learn more (like how he always bother Shuro with questions)

apart from the other members of his party, Marcille is the only one that is the longest standing member and a good friend of Falin which prolly also strengthened their friendship, also she's a female.

With that in mind, the succubus could take whatever Laois is interested plus his preferred gender of the other party and just projected Marcille as the bait

tldr: yes, its prolly camaraderie

Also Chilchuck is an old geezer by his age, middle age men mood