Thomas Bates is the father of Andie Bates. He is very protective of her and hides the truth about her mother being a succubus, however Thomas finally reveals it to her after the Father/Daughter Dance. He was reluctant to reveal the truth about her mother and her new abilities since he didn't want to lose his baby girl, however her closeness toward Charlie Monohan caused him to pass out which causes Thomas to finally tell his daughter the truth. (The Monster Within) He seems to be good friends with Peg Mueller, as he goes to her for advice about Andie and their situation.
After revealing the truth about her mother to Andie, he reveals that he and his wife was able to control it for years because they loved each other, only at a cost. Thomas was sick very often, which was a result of his wife's succubus side sucking his energy. He reveals the truth to Peg about the night Andie's mother died; She couldn't stop herself and he was forced to kill her. He's worried that Andie might believe that she'll be able to control her ability without Peg's medicine. (Repercussions)
Thomas loves Andie and is very protective of her.