I don't have any ideas I can spare at the moment (I need them all for myself. Lol). But I do have just a variety of questions, and maybe as you answer them, you'll be able to come up with a few ideas of your own.
Where is Tedril from? Since he's Dunmer, is it Morrowind?
How did he become a "potion master?"
Why does he shun towns and/or civilized areas?
are you on PC or console? And if PC, will you use an alternate beginning (no prisoner/Sewers stuff)?
What sort of diet will Tedril have? Or will you discover this in-game?
What is his favorite color? Or will you also leave this open?
I dunno...backstory either occurs to me randomly whenever I make a new character or it doesn't. If it does not, I don't always need to make it up just to start a new game. But hopefully those questions might spur your imagination.
HTH