...he presumably knows/knew Nualia personally, so I'd reveal a fair amount of her backstory from 5 years ago. He should be aware of Nualia's original personality, a shy, quiet aasimar girl. She should be a very sympathetic NPC. Frankly, though no one was especially abusive of her, she generally wasn't well treated by Sandpoint's otherwise nice citizens. Father Tobyn was a strict father figure, and she was always viewed as an outsider when she walked around Sandpoint. Townsfolk constantly approached her for embarrassing/awkward requests even as a child, boys presumably showed a lot of unwelcome attention as she grew older, etc. Then there's the whole secret affair with the Varisian lad (maybe she confided in the PC about it?), the pregnancy, Father Tobyn's stern reaction, the miscarriage, her coma, and finally her fiery death. Lots of angst.
The point is, the PC should have a lot of insight into Nualia's personality and tragic history. Lots of room to weave her into your PC's background. Lots of fun for the DM! :)