Here's my two cents on Gale. I definitely think he's being on some level manipulative. There are just moments when his manner and approach feel... less than genuine. Moments when it feels like his interactions with us are especially considered and curated to get the reaction he wants. I also think that he's still holding something back about the whole Mystra/orb situation. I don't think he's lied about anything he's told us, but I think there's still some details that have yet to be revealed that maybe paint him in a less than charming light. That having been said, I still think he's ultimately trustworthy. I think that any manipulation he's engaging in is ultimately in service to dealing with the orb, an existential threat that could kill not just him but everyone for miles around. Which I think is fair and reasonable. The threat it poses is big enough that I'm not going to fault him for putting a bit of extra effort into ensuring he has help dealing with it.
So yeah that's my thought on Gale: Manipulative? A little bit, non-maliciously so.
but you haven't explain what is the active of gale absorbing the "shard of dark magic" .
gale claims this is "for love mystra", but why a potential big threat can be seen love??
