One of the most interesting aspects of A.P. Bio is the fact that all four seasons happen in the same school year, over the course of a few months. As such, when a student suddenly disappears from the class, that kind of stands out to the audience. This was the case with Devin, who was at the center of a major Season 1 storyline that suddenly came to an end when the character was unexpectedly gone in Season 2.
Like much of the A.P. Bio class, Devin was sitting quietly in Season 1, Episode 1 when Jack Griffin drove his car into the sign outside of Whitlock High School. Devin was a dark soul and a bit of an anarchist, so he immediately appreciated the chaos Jack brought to the classroom. He wasn't as big a fan of Griffin as Heather, but that would honestly be impossible. She idolizes the man.
Over the course of the first season, Devin formed a bit of a bond with Jack. In Season 1, Episode 12, Devin struck one of the biggest blows in Jack's war against his best frenemy, Miles Leonard, by pretending to be his son. It didn't quite work out as planned, but it was a huge moment for the entire project. Plus, it led to Jack seeing more of himself in Devin than he initially suspected.
That made it even more strange when Devin wasn't there in Season 2, Episode 1. He was suddenly gone from the series, with no explanation. In the real world, actor Jason McCarthy, who played Devin, moved on to a different series, leaving A.P. Bio behind. That kind of thing happens. But the strange part was that the character's sudden departure was never addressed in any capacity. He was just gone.
This definitely stood out, as he was part of a major storyline with another classmate. Dan Decker started off the series as Devin's bully. Jack brought Dan into the class in an attempt to force them into getting along. And it worked. By the end of that first season, Devin and Dan had become friends and were at the beginning of a new arc in their relationship. But that never got a chance to play out, as Devin disappeared.
On top of that, the Season 4 finale added another big wrinkle to the situation. Episode 8 featured a story revolving around Jack's precious Harvard pen. A flashback to the moment Jack arrived in Season 1, Episode 1 retconned the scene, replacing Devin with a student named Caleb, who became more prominent in Seasons 3 and 4. Devin was effectively erased from the series completely in this episode.
Actors leave TV series all the time. But the school not acknowledging the sudden disappearance of a student, combined with A.P. Bio essentially erasing the character from the show was a little strange. Adding to the absurdity, the same thing happened to another Season 1 student named Colin, but a lot fewer people seemed to notice his unceremonious departure. Devin leaving the series definitely caught more viewers off guard.