@Zarna I see a disconnect here between what custom characters are supposed to create and what origin characters see. I hope the 'what attracts you' tooltip you mentioned is just temporary, while we test things during early access.
Mysterious Guest: Who do you dream of at night?
Astarion: I fucking dream of Cazador, ok? I have nightly nightmares of my sadistic, psychotic Master!
Lae'Zel: I dream of my Queen Vlaakith and how I will add to her eternal glory!
Gale: I dream of Mystra, brilliant and beautiful.
Mysterious Guest, thinking only of Freudian psychology: Oooh, ok, so you want to fuck your Master/Vlaakith/Mystra. If I show up as Cazador/Vlaakith/Mystra, will that let me know you? Control you?
Astarion: No, you idiot! It will only make me (more) insane with fear and remembered trauma!
Lae'Zel: Lies and deceit! All of it! My Queen would never bestow such favor upon one who hasn't proved themselves!
Gale, lying with a smile on his face... but still taking out some mental lube: Sure, yep, absolutely. And the skimpier the dress, the better. And if you could add some 'I forgive you, Gale!' somewhere in there, that would be great.
If they leave just the 'who do you dream of at night?' part, then the dreams are even better. Because you could be dreaming of a mentor, a sibling, an adversary... stress dreams or reliving fond memories... but since the Mysterious Guest just dons their physical appearance and keeps its own pink and gold toga (identically to the Disguise Spell), the resulting cognitive dissonance can explain some of Tav's reactions.
Tav1: I just escaped a tough battle on board an alien ship, and I just throught I'd dream of my former drill master, grizzled Dwarf with the foulest mouth you'll ever hear... he once threatened to have me cleaning latrines for a month... and now he trailed his finger down my arm and told me he'd make me feel better! *shudders*
Tav2, looking visibly disgusted: I know... That cook on the ship reminded me of my aunt... She always complained about rats getting in the flour... and then she... UGH!
Tav3, looking fresh, well-rested, and eating his breakfast with gusto: I dunno guys, I dreamt of the lass I was to marry. I'd already bought the ring, you know? She told me to accept her, let her in. 'Course I'd do it!
