Like everyone else Karlach really resonated with me and I echo pretty much everything others have already said.
#JusticeForKarlach!
Alright, stop bumping repeatedly without any responses, they're not going to change it based on how many posts you spam. We get it, you don't like how it ended.
People here aren't saying that the actual ends for Karlach are trash. People are saying that her questline is so under explored compared to any other companion. Why the game gives you infernal metal after act 2 while it's useful for Karlach only but never used after the second fix with Dammon ? Why do you free Gondians inventors in an ancient Forge that took like 4 hours of game if not for Karlach ? Why Steel Watchers tell you her heart is based on an old prototype they succeed to stabilize, and you never be able to talk to them about a fix ?
It's like all the elements are here to let you have a better way than just go back to the Avernus like it was inevitable... but wathever you can analyze in all the dialogue scenes it will led to a dead end where the choice is not really given to the player. That's the problem, even more considering a game where you're supposed to write the story regarding your playthrough.
Of course if I don't care about her story, if I fail a quest, if I miss something I can expect actual ends, everyone here is ok with that. But if I do everything correct and the game gives me all required things to save her, then why is it not possible to use it ? Why her end is so absolute ? Not like she had to confront some gods or something like Gale or Wyll. Not like she betrayed her semi-god queen like Lae'zel. There is just a bit of metallurgy to be done. And in a magical world where you can face gods and cheat death, that doesn't seem like the hardest thing to do.
There are so many obvious means to save her given by the game itself without overinterpretation, so much more terrible fates that are resolved no matter what even if it requires a deus ex machina to just save a character.... that not having to ability to save Karlach with the easiest thing to fix in the whole game, the same way other can be saved is totally incomprehensible and inconsistent.
As a player who play a game which is supposed to let me explore all the way to finish a quest, there is an unpleasant taste of unfinished... It's like if in Star Wars, rebels find the failure in the Death Star security, conclude that's the only way to destroy it, prepare all the mission, and then without any explanation they just tell to Luke "we prefer die on Yavin as heroes than being Empire's slaves" and they do nothing, waiting for the Death Star to destroy Yavin.
If it was a side quest in the Groves that feels unfinished, well I don't think people would react like this. But we're talking about the quest of a main character, that's not the kind of quest you can afford not to finish or giving this feeling.