So, after the discussion over on the General Table Talk thread and actually reading the saga guidelines for Familiars, I think I'm going to overhaul Semsuhfaw. Make him a Summer Character (360xp) with a base Might of 10 (which would be 12, after adjusting for his Size).
Definitely going with the Do My Will Power, though, but I am undecided about the "Leaping Legless Lizards, Lenny!" one. I'll have to dig out my Hargreave's and see what powers snakes supposedly had.