Jamie's heard blood magic is bad in general, but right now I'm pretty sure any conversation would be just him being confused about the whole thing and therefore pretty open for being convinced that there's exceptions to that rule. Plus it's Merrill, and he's already getting the idea she wouldn't hurt anyone.

But that aside what do you think about them going out on an adventure and possibly getting lost for a bit at some point? He could also tell her stories about unicorns, although his stories involve him thinking they're out to kill him. But if she wants to see him gesticulate wildly while talking about how the beastie was ready to charge him, hey, he can do that.