In the beginning of the show's run, Thelma's lesbianism was made very apparent, along with the realization she was in love with her best friend Cassie, with whom she attended Medenham Hall.

As a ghost, Thelma displays the ability to enter others' dreams, doing so to make-out with Cassie, later to communicate with the living and to free comrades from Malachi's control.

After giving the character Leon (Jamie Davis) a potion of Ella's to allow him to see the spirit world, the three form a group who fight against Malachi - the series' main antagonist in wake of Azazeal's mid-season departure.

Malachi eventually seduces the entire student body romantically or by promising them their greatest desires, creating an army of succubi and incubi that makes him too powerful for Ella to kill.

In the programme's conclusion, after helping Leon to save Ella's life, an indestructible Malachi sacrifices Roxanne while the entire school is burnt to the ground.