[@Sep] Just to probe things a bit as I work on a character, I want to ask if this sort of thing might potentially work: 

So there's a child found to be force-sensitive, and they are taken by the Jedi of course to be raised. Turns out after some time, however, they have a distinct affinity for the dark side. Of course this isn't good, but they don't want to just send the child away to become a potential danger. So a grizzled old Jedi is basically tasked with their care, and taking pity on them and becoming attached trains them on the light side to try to help them keep things in check within themselves.