StaleBread
I be being, ...and that is all
I think it could work if you had Leo be very wary of Greg since Greg entered the cult, even tho Gregs awesome, like Undead said, he's not a bloodhound. He won't be able to sense Leo's anxiety from the other side of a crowded room. And Greg finding out about Leo could be a plotpoint? Like, Greg finds out because he's Greg and the cookies Leo ate smelt green or something(XD), and Greg being smart doesn't say anything about what he found out to Leo, instead reporting his findings to Granddad. Granddad is upset, but decides to act rationally,I really like him maybe I'll find a way
'What exactly has Leo uncovered? Does Leo have outside help? Have their convo's been recorded?' stuff like that.
Granddad acts behind the scenes to figure out exactly what Leo knows and who he is, and maybe see's potential in trying to make him into a member anyway through psychological manipulation since all Leo's trauma is a good way to get into his head? Maybe Leo even becomes the next loyalist zealot through Granddad's effort and becomes a double agent, telling Granddad what the police know and what they're suspicious of etc.. While Granddad still has Greg keep tabs on Leo to be sure he 'stays in place'?
Up to you guys though, just throwing in my thoughts