Betraying a cult of Levistus, Temin made a deal with the Duke of Iron to escape a situation that was about to end very poorly.
She spent the next years developing her new powers, eventually stumbling upon the Sea Urchins in an abandoned cavern north of Neverwinter. She fought beside them against mutual enemies, and bonds were formed. She'd missed being part of a group, and Sea Urchins were warm and welcoming. It wasn't long until Temin was relaxing with the group in Steve's tavern, happily consuming mozzarella sticks and figuring sure, why not launch a revenge attack against the entire nation of Thay?
She has a deep distrust in the bond they've formed with Korda, a little more knowledge of the hells than is strictly normal, a known dislike of the cold, and - though she is devoted to an entity of pure evil - somehow serves as the heart of the party.