Imaculata
Hero
Thanks @Quickleaf. I'm not very good at intrigue, but I like the idea of making Tholzar more nuanced, so he's not just some cardboard cutout that the PCs can kill and forget about.
A friend of mine once introduced a drow npc that was also kind of gray. I hate that I can't think of this drow's name right now, but he was a fantastic character. And the group liked him so much, that whenever another DM took over, he'd often find some way to have the drow make a cameo appearance.
It was never clear what side this npc was on, but the party would often be put into a situation where they had to rely on his help for something, and they knew he couldn't be trusted. These sorts of characters can be a great addition to any campaign.