It kinda makes sense for a group of people who happen to share the same problem (a tadpole) to stick together, especially when other folks will perceive them upon finding out about their condition. For exmaple, there are many reasons why the characters would agree just to wait for the MC in the camp.
Especially in the case of Astarion it seems weird that he would simply wait by a campfire for people he probably despises and feels are inferior to him to do whatever instead of just traveling to BG by himself to study his newfound powers and/or go back to his luxurious life...
I don't think he despises his companions or thinks them inferior. He believes that every man is out for himself in the end, so he is self-centered, opportunistic and careful about forming long-lasting connections for his own safety. He is still exploring his newfound freedom, while being really,
really bad at hiding his true nature for long. If the MC is fine with him being a vampire and lets him drink blood of their enemies, Astarion knows he is doing better than he expected. He is accepted, he can feed freely and he doesn't have to bother with playing the perfectly normal, totally-not-a-vampire-spawn elf. Additionally, he doesn't have a plan for now, except for "get rid of Cazador", and even though he isn't impressed by the MC's promise to deal with Cazador, he hopes that at least the MC will stay alert and give him a heads-up. So, if the player doesn't do everything they can to max out Astarion's disapproval, he has many reasons to stick around.
Same for SH, why would she care to wait for you instead of trying to rejoin her shar cult, same for the gith who couldn't care less about non-giths
For Shadowheart staying at the camp means more time to explore her mystery box safely. It maybe makes sense for her to disappear from the camp (if not in active party) and then come back without explaining anything, since she is already the most tight-lipped character in the group, but not storm off completely. With Lae'zel though...On the one hand, she would have started looking for the creche as soon as she learnt about the githyanki patrol. On the other hand, she isn't familiar with Faerun and there are many hints that she is not 100% confident about the creche. She keeps talking about it, while her interactions with her kin and her anxiousness afterwards gives us a clue that something is off. Maybe Lae'zel is also open to alternatives (Halsin, etc), but because she looks down on Faerun and other races, she won't say it out loud.
same for Gale - why doens't he go find his magic food by himself instead of waiting for it at camp and risk auto-explosion, and same for Wyll who is supposedly well able and willing to adventure on his own.
Given that Gale is covered in bandages in his official art and Auntie Ettel mentions him rotting alive, maybe he was meant to be a powerful wizard with a slowly deteriorating health. A guy like that can't just brave into the ruins and goblin forts on his own. That's why if you don't give Gale artifacts, he resorts to making a deal with the devil.
In general, almost every party member has a skeleton in the closet and kinda bonds with the MC upon revealing it. If the MC is understanding and doesn't push them away, they see benefit in traveling together and see no problem with staying at camp. At least, for now.
