Sully was Sam's protector when Sam was nine years old. He always accompanied him until Sam later rejected and left him. He later moved on from Sam with severe heartbreak.
At some point after Sam's leaving, Reese and her twin sister Audrey were protected by Sully. While playing a game of tag which led into the street, Sully did not see an oncoming car and Audrey was killed. The accident traumatized Sully, and caused him to not want to work directly with children anymore because he was afraid to hurt another child.
After his fellow Zanna and friend Sparkle was killed, he located Sam and teleported to the Men of Letters bunker. He begged Sam and Dean Winchester to help him deal with his friend's killer. After another Zanna, Nicky, was killed, he got a distress signal from Weems and located him. When he and Dean looked for some medicine and bandages to patch Weems up, Weems revealed to Sam that Sully was heartbroken after Sam rejected him.
Sam later apologized to Sully about what had happened, and told him about the release of the Darkness, which Sully has aware of, and promised to fix it all. He also told Sully that he did not want to enter Lucifer's Cage. Sully suggested he run away.
After Reese captured Dean and lured Sam and Sully to the warehouse with a text from Dean's phone, she told them what she had been through after her sister's death, and how and why she was killing Zanna. Sully offered to let her kill him to stop her from murdering more Zanna, but Sam, Sully, and Dean were able to talk her down, and change her mind about killing Zanna. With the problem solved, Sully said he would continue to check on Reese, and said good bye to the brothers.
Powers and Abilities
- Invisibility - He was invisible to humans unless he allowed a human to see him.
- Telepathy - He was mentally connected with other Zanna.
- Teleportation - He was able to teleport into the magically warded Men of Letters bunker.
- Magic - He had a limited range of magical powers typically passive in nature including conjuration, empathy, and glamouring.
- Magic - Although invisible to humans, a spell could be cast to allow humans to see him.
- Zanna-killing knife - He capable to be killed with it.
- The First Blade - It can kill anything.
- Death's Scythe - It can kill anything.