On Monday, Oliuwadamilola Ogunyankinnu, 27, of Enfield, appeared at Stratford Magistrates’ Court charged with the murder of Sullivan.
The 21-year-old, who was known as Fin to friends and family, was a film student at the London Screen Academy.
He was found with knife wounds on Primrose Hill at about 18:40 BST on Tuesday 7 April.
Holder told the court: “A fight broke out involving two groups of males.
“One group of males attacked the deceased victim, and the other group – including the defendant – attacked back.”
Abdulqadir spoke only to confirm his name, address and age during the brief court appearance.
He is due to appear at Inner London Crown Court for a plea hearing on 12 May.
His case may be linked to hearings at the Old Bailey involving Ogunyankinnu, who is due to appear before a judge at the Old Bailey on Wednesday.