I'm glad you agree with my amateur assessments. I don't know how to write either, I just flail at the keyboard for a long time until I see a lot of words on the screen, and assume that no one will read them.
I also read and agree 100% with your assessments.
One thing with Shadowheart, Astarion, and Lae'zel is that how friendly or insulting their dialogue is GREATLY depends on what and how you speak to them. In the very beginning SH says she wishes to remain private (when asked why she was on the nautiloid). This is a HINT that you shouldn't pry into her affairs/background. Most of her nasty comments are when players ignore this and ask her all the questions. If you just give her time she opens up to you and will respond to questions. Lae'zel is also like this . . . waste time asking about random crap and she gets pissed off . . . she wants to deal with the tadpole and anything not directly furthering that end she doesn't have time for.
Larian provides us with lots of dialogue options . . . but unlike many other RPG games where we are conditioned to 'ask all the questions', ie select all options on the left before progressing, this isn't the case with Baldur's Gate 3. It's important to be preceptive and approach your companions in ways they will respond well to (assuming you want to foster a good relationship). You know, kinda like people you meet in real life! 😉 Actually Larian does this in all aspects of the game (gives us lots of options to get ourselves into trouble!)
And I love this about the game!
What Firesnake and trengilly said. I'll sum up my own opinion regarding the companions below:
Shadowheart - at first I liked her. She seemed reasonable and the fact that she wasn't pissed at me for failing to get her out of the pod (she was even grateful!) made me happy. I noticed her somewhat drawn back character, and soon I noticed that each time I talked to her - she got hostile even though I didn't exactly try to converse with her, I was simply checking if she had any new lines without digging into the stuff like "We should get to know each other!" since she quite she made it quite clear that she valued her privacy - I thought I'd just check in on her time to time and leave her be. But she grew increasingly hostile to a point where I really started to dislike her - either I cared too much, or not enough - like some type of weird abusive partner. I really started wonder what the F her problem is - and so, as I was digging around on these forums (which I enjoy doing a little bit too much for my own good) - I came across the datamining thread... And well, without spoiling it for those who dislike spoilers - her behavior made sense. Much cause of what Firesnake stated above. So now, I realize her character isn't poorly written and that she isn't trying to be an abusive girlfriend - she is just confused and hurt, and sometimes that barrier comes crashing down (like the celebration after the goblin slaughter xD) - but only for moments at the time.
I would find it extremely unreasonable for someone as confused as SH to just let us in during Act 1 - that would be completely out of character, as far as I can judge. What she'll be like when/if we actually grow a bit closer remains unsaid.
Astarion - I actually love the guy (not romantically though - he is not fit at all for my character). He is very charismatic and as a player I've had plenty of laughs at his remarks and comments. My character is less amused though, but his behavior makes sense as long as you're aware of the *not-so-secret-fact* that he is a vampire. It makes even more sense if you've been digging around the datamining thread to see more bits and pieces of his past. Even though I am struggling to see why my character would keep him around, from a roleplaying perspective, I'll try to find a reason to keep him around because 1) I like having a competent thief in the party and 2) I REALLY wanna see how his story turns out.
Lae'zel - I honestly don't even know how people can dislike her as much as some people seem to do. She is not even throwing that many insults, even when she is mad. Even for someone completely unfamiliar to the gith culture (such as myself) - her characteristics makes perfect sense. And, once again, if you don't mind spoilers and visit the datamining thread, you'll find a lot of reasons why she is the way she is. And a lot of interesting theories on her development.
Wyll - ... ... Probably the person I like second least. He seems to be covering up his narcissism with heroic deeds. Now, I know that a lot of people reason that because Wyll got his powers from his mistress, all of his actions are automatically neutral at best - but never "good". I disagree with this logic - I do not know as much about Wyll as I know about Astarion and SH, or even Lae'zel - but as far as I do know (from just playing the game and a liiiiiittle bit of datamining *cough* mirror *cough*) - I can safely say that I do not, personally, deem the bargain in the first place out of hand. Then the fact that it escalated to the point where he got himself is an entirely different point. I consider him somewhat of an power-addict; it started off as wanting to do good and bring those who done wrong to justice, but ended up with him just wanting to grow more powerful for the sake of... Well, being more powerful. As long as he keeps aiming at bad folks, the actions are reasonably justified (but up for discussion), but I am not so sure that he'd stop even if all evil was wiped out. Not if it costs him the title "hero". Soooo, no. He is a big no for me.
Gale - actually the individual I like the least. And that is NOT cause he is a poorly written character, quite the opposite. I just believe there are several reasons to be cautious of him (and that is not just from data mining, there are loads of speculation threads regarding Gale's nature based on ingame information only). I'll put a spoiler tag here, just in case. Do not read if you don't mind INGAME spoilers about Gale (not sharing datamined information).
First of all, just the tiny fact that he didn't have a tadpode response to us, unlike literally ALL other tadpod-infested companions / NPCs.
Second of all, he is incredibly charismatic and funny, just like Astarion, but I highly question his morals just by the fact that he wants you to cheat on your particular partner. Did not happen to me personally as I didn't romance, but I observed that he had asked multiple characters to cheat on their chosen ones in one of the Gale threads.
Third of all, the fact that he has this artifact within him - and even tell you that he is feeling unstable/hungry ("I need to eat the next artifact we find - PRONTO") AND STILL DECIDE TO STICK AROUND is absolutely baffling. That is NOT what a *good* (as in opposite of evil) would do!
Fourth of all, and while he still sticks around with this bomb (apart from the tadpode, assuming he actually has one) WITHOUT TELLING US for a very good long while.
Fifth of all, he seems as obsessed as Wyll with being the greatest of all.
In short - I dislike him as a character and I definitely would not trust him with anything at all. But I do find him endlessly interesting, as a character.