SECONDED SO HARD. It would be amazing to see that explored further.
I would be thrilled if they brought back Nathan Harris. I always thought he was one of the most interesting characters they’ve ever had and I loved how complex his connection to Reid was. I’d love them to bring them back as Reid’s stalker or as an unsub killing to get Reid’s attention or punish him (he DID beg for Reid to let him die) or “recovered” but fixated on Reid. Because there is a lot of unfinished business between the two of them and a lot of unhealthy attachment on both sides.