I'd more expect Gale to accept you as his lover, and then attempt to mantle Mystra onto you, in an effort to have Mystra as his lover again, more or less obliterating 'you' in the process, but hoping to wrangle it so that the new being, that is more Mystra than you, still loves him.
But yes; I'm not accounting for external meta at all in this, and that's a deliberate choice I'm making, because I don't feel it's fair to be suspicious of a character because "well they always do that". Maybe I'm just an optimist.
I had a much larger post written out, but it's not really going to progress much or help much, I don't think... But I'll post these bits of it, just as points of interest or order:
- No, I didn't play Dragon age, and I don't consider references to other characters in other games to be relevant here. They may even be misleading, since they are exactly the sort of thing that causes people to read things onto other characters that are not actually there. If you're inclined to think suspiciously of someone based on a past encounter with someone else completely different, that's personal bias, not a fair assessment of the person in question. If anything, referencing other characters in other games as your 'reason' for being suspicious of this one is a strong indicator that your perspective is not fair or objective, and that it may be worth your while to reflect on why exactly you drew those conclusions in the first place, and checking if they're still valid when you remove the 'because someone else did that' element.
- The magic practiced by Netheril is not dark or sinister or nasty (well, no more than many types can be, and it is often used that way, I will admit... but inherently it's not); the netherese empire was a magic-based society and they practiced arts the magnitude of which cannot be replicated today (literally can't, since Ao has since placed limits on the level of magic that non-divines, and even divines, can wield). They weren't much for respect of the goods, and much of their magical experimentation and exploration was aimed at supplanting them and casting them off, but the basic point of it is that their magic was highly advanced, and studying what is left of it after the fall of their empire is the pursuit of a great many wizards and other arcanists once they reach a certain level of skill. There's nothing suspicious about Gale being versed in information about netherese magic, and there's nothing to suggest that he uses it directly. Many magical creatures with long memories are suspicious of netherese magic at a superstitious level, because it was netheril that ended up destroying the weave itself in their folly, albeit only temporarily, and it destroyed their empire. So, a lot of people are leery of it, but there's nothing actually wrong with it, per se.
- It's also not surprising that Gale didn't 'sense' netherese magic at work on the tadpole, because he is a wizard, not a sorcerer. He Can't feel things like that, and can only be aware of them by evoking spells designed for the purpose. His weave scene was special, and remains special even if you're also a caster, because it's a uniquely designed spell that he's using to allow himself to actually feel the weave, and feel magic, directly – something that wizards cannot normally do. I will admit caveat to this, in as much as it's dubious that Larian are paying attention to this nuance at all... they may not be, in which case (if Larian are assuming he could feel things just by being close to them etc.), then by that definition, he should have, yes.
- In game; Gale has a tadpole. This is not really up for question. When controlling Gale you can go through all the various things that talk about what you feel your tadpole doing, and you have all of the tadpole related dreams, and you can undertake the various activities that use the tadpole, or get it treated, etc. Gale has a tadpole.
