Ruelle was a succubus who was expelled from the Ubus Plane for unstated crimes. She preyed on very young males, often those who weren't adults, and children of immortal species.

After her expulsion from the Ubus Plane, Ruelle took up residence in the Woods of Murk. The proximity of Conall Keep, enabled her to meet Uilleam MacRieve, and she began abusing him from when he was ten. She used her strew on Uilleam to bind him to her, and would often use the effects to punish him by preventing him from being with her for days. This lead to Munro and his parents to discover the relationship.

She was killed by Douglas MacRieve.

Uilleam was not her only victim, and not even her only victim while she was abusing him, an unnamed Vampire was with Ruelle when Doughglas s killed her, and he killed Ailis in a misguided revenge.