My ideas are all really vague and sketchy at the moment, but Remus is still a werewolf and a wizard, who finds Sirius, who is a genie, and is also the last remaining guardian of a magical forest. The history of the forest comes out gradually and it's kind of a retelling of canon eg when Remus hears about Lily and James from someone else Sirius says, 'I as good as killed them.' I'm also planning lots of nature symbolism and stuff about four elements/seasons etc.

I've never written anything like it, so it might all go horribly wrong but it'll be an experience! :D