In the old BG games, we've met companions along the way, so I'm pretty sure, we haven't been introduced to all potential companions. From the ones in this first area, only Karlach seems to be confirmed? I said in another thread, that I would love to have Alfira and Halsin as companions, love them both.
As for the spider - I think, that would be more of a summon? But I would love to see that. I liked the phase spiders in the Whispering Depths and would love one of them as companion ... even if it would be a bit shrewed, since you basically kill their mother.
I don't think, that Us would be so friendly now to us - every other intellect devourer attacks us now on side, despite them being friendly on the ship. I think, they know by now, that we are not allies anymore - maybe another sign, that the tadpoles in our heads have been tampered with and altered.
I'm ok with keeping the owlbear as a visitor to my camp. It's nice, when he is there, but I somehow have to wish, to keep him out of harms way after all he went through (I didn't kill the mother, she showed me the little one and I left them alone. I did fight and kill her at first, but the scene with the baby was so heartbreaking, that I reloaded).
As for unique companions - I would like to have a Myconid in my group - not temporary as it is the case now (temporary because I don't attack the Myconid colony, like them too much). They are an interesting bunch.
A Myconid could be cool, even as just a camp resident.
And I think that the hostility of the other Intellect Devourers is the purpose of the uh mutilate check on the ship, so that Us doesn't turn on you, and only bonds with you. Which is kinda messed up but matches the game's tone.
Also I do feel a bit bad killing the Cub's mother, though I find more often she attacks me outright and I get that messed up scene of the Cub just eating their mother...
