- He's not an alter, or a demon: he's the ghost of Randy's younger brother, who ended up being Jeff's fourth victim. After they died, Sully decided to possess Liu to try and use him as a puppet to kill Jeff for revenge, but the plan failed miserably.
- He died when they were 16, but due to possessing Liu, he ages along with him. So, currently, he's 29 years old.
- Sully has their own form, a monochrome version of Liu with a slightly different outfit, glowing white eyes, and shorter, curly hair. He also has sharp teeth.
- Their voice is rather gruff and raspy.
- It takes a lot of energy for Sully to take control of Liu, so he mostly uses their physical form.
- He didn't develop bipolar disorder until after they died.
- He utterly despises Jeff, and as much as they've tried, he's never convinced Liu to get revenge on him; eventually, he gave up. Sully doesn't like admitting it, but one of the reasons they're bitter about Jeff and Liu's close bond is that he wishes he was that close with their own brother.
- Because he has mostly Mexican heritage, Sully is fluent in Spanish. It's also their first language.
- As a kid, Sully had curly ginger hair and freckles, and they always wore a blood red knitted beanie his mother made them. He was also noticabely short for their age, which he was constantly teased for. At 16, he was 5'4.
- Sully never knew their biological father, so Randy was his only male role model in their early years. He came to look up to Randy a lot, following him everywhere and joining him in breaking the rules and bullying the Woods brothers. The two were as thick as thieves, but Sully couldn't help but feel as though he was being treated more as a sidekick than a brother.
- When he was a teenager, Sully was a Twitch streamer. He had about 300 subscribers on Twitch. Randy would often sabotage their streams for fun, and Sully always got annoyed when his viewers would simp for Randy.
- He always knew that something was wrong with Randy mentally, but they didn't know what to do about it.
- Despite getting into trouble almost as much as Randy did, Sully turned into a mama's boy at home, helping Andrea around the house and doing their chores and homework as soon as he came home from school. He did this partly out of guilt.
- They didn't resent Dario as much as Randy did, so he was a little nicer to him. He actually found out about he and Randy being related to Jeff because of Dario, but they've never told anyone - not even Liu.
- When Randy and Keith were being arrested for setting Jeff on fire, Sully was struggling against Andrea's grip, trying to rush out to them. But they had to watch their beloved older brother and one of his closest friends getting pushed into police cars and dragged off to the police station. He was in a funk up until Jeff snuck through their bedroom window and murdered him.
- Sully secretly has a soft spot for small animals, like bunnies and ducklings.
- As much as Sully tries to act like a tough guy, he's a simp when it comes to Vailly and a bit of a pushover when it comes to the others. But Sully still has the power to give Liu nightmares and headaches.
- He partially blames Randy for their death and feels left behind by him. But as much as they've tried to hate him, he can't help but still love his big brother. The two of them still don't get along, even though Randy has tried to reach out to Sully.
- Admittedly, he doesn't know how to feel about their niece, Arielle. But he was secretly touched when they learned that she had been given his old beanie.
- He never admits it, but Sully is sometimes scared of Liu - in reality, he always was.
- Sully loves rap and hip-hop music. Their favorite artist is Megan Thee Stallion.
- As a teenager, Sully was often teased by his brother and friends because they all knew he was going to be a bottom in their sex life. Sully hated it.
- He can break dance.
- Sully's tears are black in color.
- They're the type of person to send his friends ridiculous memes in the middle of the night.
- He never learned how to drive and is kind of scared to.
- He can be extremely stubborn. They also don't like opening up to people.
- Sully loves pulling pranks.
- They like chewing on bottlecaps for some reason (idea by the lovely Ominous_Scarecrow).