AJ Styles was removed from WWE programming in September after Jimmy Uso and Solo Sikoa attacked him backstage on SmackDown to ensure that John Cena wouldn't have a partner at the Fastlane event. LA Knight chose to side with The Cenation Leader, and the duo won at the event. However, The Phenomenal One may hold some grudge against the pair.
While it was already noted that he returned to SmackDown and allied with Randy Orton, he did so with Knight, too. However, he attacked The Megastar towards the end, potentially confirming his heel turn. It's possible that Knight and Styles could feud in the lead-up to Royal Rumble, with AJ reasoning that LA took his spot at Fastlane.
After the dust settles between them, Styles can turn his attention to another significant star, John Cena. The Hollywood actor could return to WWE en route to WrestleMania 40 and begin to tease who he could feud with, but AJ will spoil his return by attacking him from behind.
It was noted that John was the person who endorsed Knight, which led to the latter having a title match with Roman Reigns. Styles could also say that Cena replaced him immediately with Knight and quickly forgot about AJ when he was injured.