Curly is a member of the Doomguard who was caught on the Ship of Chaos when it was stolen in the Abyss by some Demons.
The Party found him in a cage with several other, insane, captives, and rescued him. While the Party was fighting on the Ship of Chaos, he found a key in the courtyard of the fortress they were in, and wanted to search the place for treasure, by himself. Toby managed to restrain him until the party arrived, and Reinhalt intimidated Curly into giving up the key.
Curly never really trusted the Party after that, although was somewhat mollified by Helga's giving him part of the treasure they had found, and the Bishop's friendly talk with him. They parted ways after bringing him safely to Sigil, after the Bishop said he could get help from us if he needed through Savrin.(29)