1. Gale's load screen image; Psycho Gale 2. Gale doesn't mind link with you 3. Gale knows about Netherese runes and magic, and what is potentially keeping our tadpole at bay? Netherese magic. 4. He's power hungry 5. He acts all good, but I see snippets of him trying to learn secrets about Lae'zel and SH especially. 6. He's not opposed to necessarily playing games with a devil 7. He supposedly loves Mystra but doesn't say a word about SH being a Sharran cleric, and Mystra hates Shar
I think there's more, but ultimately I started looking at him differently the more I played the game. He started becoming less good to me and more potentially manipulative.
I will say, though, contrary to that, if you are evil, he does seem to genuinely feel bad about killing everyone, and he will leave.