The nein have to sneak into a party in disguise, and they all find different ways of getting an invite, and Caleb's way in ends up being decided by the ~powerful NPC that brought them the reason for having to sneak in in the first place. And the NPC gets Caleb into the party by bringing him as their plus one. And then, while they're all at the party, said NPC uses the relationship cover story as an opportunity to get extremely handsy with Caleb, and verbally disgusting, knowing that Caleb won't fight them to avoid blowing his cover.

+++ for a different NPC who knows it's fake being like "oh wow they're really good at faking this!" and not seeing how uncomfortable Caleb is, and meanwhile they're having to physically restrain Beau from going over and committing a murder because as satisfying as it would be, by blowing their covers they'd probably all end up dead, Caleb included

++++++++ the rest of the M9 being EXTREMELY protective over Caleb when they're finally out of there, and whether it's friendship or more making sure he knows how much they love him