| defensor |
Very interesting post, OP. I shall make good use of it, thank you. I do think the storyline presented in the book for Tristian is a disappointment: so he's an aasimar, very well. What difference does it make when that reveal happens? None, he's still the same character the PCs followed throughout.
I sympathise with the choice of not making the storyline solely about him, but it is much easier as a GM to cut things than to add it, so if that was indeed the concern, the book should have been presented the other way around: with his original plotline as a fully-fledged option, and a sidebar offering the alternative to cut it.
I also disagree that Tristian's role as the mole robs agency from the characters: if he is used well, he'll be a beloved NPC by the time the Vanishing of Varnhold happens. A betrayal is an interesting story moment, and presents the PCs with important choices on whether to redeem him or pursue other goals.
As for better involving him in the story, Tristian can replace Jhod as the early campaign support cleric, which has worked well in my table. Jhod is a blander character, and easily cut.