This really comes to play in a fun way later, after talking to Mystra. Gale will justify being given ultimate power by saying something to the effect of, "you know me to be a moral and reasonable person, right?" The very same Gale who you can convince to do atrocities and break the rules of magic with.
This is such a fun aspect of Gale that is not often talked about. He is polite, even caring towards the struggle of others, but his moral center is aligned with your character in such interesting ways. The ways that he mirrors the player characters morality makes him a real joy on both good and evil playthroughs!
now I'm curious...who is Gale morally imitating?
I know you haven't played the game so I'll write this through that lens, but I think he imitates the player! More so than the other companions, he is willing to go along with what you suggest including some pretty morally abhorrent choices (which he pushes back against... but he doesn't leave unlike two of the more explicitly good characters). He voices support for seeking power even when it's through pretty questionable means. I have often said he's more nice than good and part of that is if he develops a close relationship with the player, he'll go along with their version of morality, the prioritizes the people close to him far more than any broader moral obligations... this can be beautiful like wanting to stay with you if you become an illithid brain eating monster but also beautiful because you know he'd definitely help you source the brains to eat. he'd find a way to justify it for sure