Firstly, the arc of the beloved character has not ended with the show's finale as opposed to other members of the original cast who either retired, found a new job, or even died throughout the course of the show. In the finale, the only two remaining members of the original season 1 team were Matthew Gray Gubler and A.J. Cook playing Jennifer Jareau. JJ returning to the reboot actually reminds the show's fans about the unfinished business between her and Reid.

In the finale of season 14, while being held at gunpoint by an unsub JJ confessed that she had always loved Reid. And though this confession led to nothing in season 15, fans wonder if the reboot could spark the romantic feelings between the couple.

With that in mind, it could be difficult to explain the absence of the boy genius without some forced cooked-up story. Reid has never left the BAU, even after some pretty traumatic events in his personal life and career. Spencer Reid survived multiple personal losses, a prison stint, an addiction struggle, and his mother's deteriorating health without ever leaving the team. So what could have made him leave this time?

But the main issue with Reid's absence is his irreplaceability for the BAU team.

"I noticed that a lot of critical points or deductions are made by either Reid or Garcia. Reid would come up with a really obscure fact or rare disease or read like 100 pages a minute to help solve the cases.

And Garcia would narrow down 35 million people to a single person or use her godly tech/hacking skills to access almost everything they need. Without both their particular skill sets I'm curious how the BAU would solve some of their more difficult cases," a fan explained.

And the cases the BAU team will be solving in season 16 do promise to be extremely difficult.