There's a pretty sharp divide between the people Keltham hired before, and after, he started worrying about whether being in his presence or being important to the story might cause people to have more realityfluid. The latter tend to be cheerfuller, happier, and to be headed towards afterlives they're happy with. The former kinds of people have grimmer stories, which they can't tell Carissa Sevar about, because once Keltham realized what he might be doing wrong, he ordered everybody present to not talk about any bad things that had happened to them in the past so those bad things wouldn't get more realityfluid in them retroactively.
This person wearing the holy symbol of Nethys has led a peaceful life for a Nethysian. He's in the pro-doom faction. He's only a first-circle cleric, and only uses his divine spells for harm reduction even so, in case doing otherwise would risk Pharasma looking through him to see Nethys. He's on the Project because he has an incredibly encyclopedic knowledge about spells, items, monsters, all the magical details of the world; and since that isn't Nethys's power he can use that wholeheartedly to assist Keltham.