It's a quite interesting idea, there are not many fiend NPCs around: the only other full-fiend NPC i can think of is Fall From Grace from Torment, but that's a completely different setting, where those creatures are far more common (Sigil). Anyway, the way she interacts with the Material Plane could be very particular, since she's grown *elsewhere*.
Just one thing which puzzles me: I'm not sure if fiends are born like mortals, ie whether they have parents or not... shouldn't they rather come from dead souls, either supplicants in Baator or kidnapped from the plane of fate, while they were waiting for their judgment by Jergal and Kelemvor? not sure though, or perhaps they can come into existance in both ways...