David Sullivan
is a young African-American student at Dalton Academy and a boarder of Windsor House. David is a part of the 'Warblerland' group, where he is known as the Mad Hatter.

David has a very close relationship with his best friend Wes, even giving him a New Years "kiss." He has a girlfriend named Katherine Rivers, who has an as of yet unidentified medical problem which caused her to undergo surgery right around New Years. They have been dating for five years and he is very devoted to her. He even sang her a cover of "Kiss From a Rose" over the phone with the other Warblers backing, making her cry.

David blames himself for the incident (from the sounds of it: a car accident) which caused Katherine's heart problems. Her surgery near New Years was her second surgery due to cardiac arrhythmia. Due to her body not taking the surgery as well as they would have liked, she needs a heart transplant, or she will die. David did not take the news well and shut his emotions down for a period before the Windsor boys made him talk, and convinced him they were there for him.

David has a very 'preppy' style according to CP Coulter, sticking to slacks and blazers while out of uniform.

He is involved with three main sports; badminton, swimming, and soccer. He was not granted the MVP for their game against St. Patrick due to League rules but would have otherwise recieved it for his performance as the goalie for the Dalton Kings. (In the battle against St. Patrick, he single-handedly defended the goal from every single attack). He is virtually loathed by the whole league for his amazing defense.

David has one of the highest GPAs at Dalton and can get very stressed over his marks, and he had a problem with Murdoch when Murdoch accused him of having a senior student write one of his term papers.

David took over control of Windsor house when Blaine was ill, something which he found as some sort of karma as he is one of the usual troublemakers himself.

David seems to be very protective of his fellow Warblers (as they all are) - but especially of Blaine, and still harbours a deep anger towards Logan after what he did to Blaine.