WARNING: The following contains spoilers for Season 3, Episode 7, of Westworld, "Passed Pawn," which aired Sunday on HBO.
The theories about Caleb Nichols have run wild since before Westworld Season 3 debuted. Introducing a human character into the main narrative was always going to spawn theories, especially on a show where those assumed to be people turn out to be secret hosts right and left. (Though you have to admit, William's realization that Stubbs was a host too was pretty hilarious this week.) But no one guessed right when it came to Caleb.
The key to Westworld's Caleb twist rode on the fact that everyone would guess he was a host. The most unexpected thing the show could do was prove he was human the whole time. Even though the series confirmed, again and again, all season Caleb was a person and not a host, it was still a shock when the penultimate episode assured us Caleb was human for the final time.
So what is Caleb's connection to Dolores, and why is he on the side of the war that isn't fighting for humanity? It turns out that just because one is human doesn't mean one can't be reprogrammed.
Caleb's Story
After all the hoopla and theories, it turns out Caleb is human. He was not replaced with a host after being killed on an army mission. Delos did not build him, nor did Dolores, or anyone else. He and his buddy Francis were the only remaining survivors from a mission to Ukraine to take out Russian insurgents, honorably discharged, and sent home. But didn't Francis die in the war? No, that is a reprogrammed memory. All of Caleb's memories were reprogrammed after he got home. Francis was too.
When they arrived back in the states, Rehoboam did not decide Caleb would commit suicide and put him on a modest loop of construction work. Instead, it flagged them both as outliers, dangerous leaders who could foment revolution. They were taken to the same facility where Serac's brother was locked up, and like everyone else there, Serac attempted to reprogram them. Except something happened with these two that rarely happens there: It worked.
Serac's Treatment
Caleb and Francis, now brainwashed and reprogrammed to be obedient followers became Serac's assassins, taking out those who were dangerous to the well being of the human race, and rounding up the rest. It wasn't until they accidentally took in the head of the pharma division that things went sideways. It wasn't about the roundup. Caleb was becoming deprogrammed, and Francis was ordered to kill him.
But Caleb's curiosity was too quick for Serac, and his shooting skills too fast for Francis. Caleb shot first. He killed his best friend. Caleb was the dragged back in, reprogrammed for a final time to believe Francis was killed in action, and then stuck on a depressive loop to off himself conveniently without further issue. He might have too, if Dolores hadn't found him, shown him what Rehoboam was, and put him back on that outlier track Serac worked so hard to keep him from.
Team Make It Stop
The irony is that Caleb doesn't want to destroy humanity, even though that's how Bernard is terming it, and his fight against Serac makes it an easy dichotomy. Caleb wants to destroy Rehoboam and the Serac program. Seeing all the outliers, hundreds and hundred stored in the warehouse, all in suspended animation, await reprogramming has horrified him. He wants humans to be free to do whatever they wish, and if that means destroying themselves, so be it. At least it's their own choice.
But Serac doesn't see it like that. To him, giving freedom to humans takes away all security. He's so close in getting his hands on the Sector 16 data, which should help him reprogram all humans so that there are no outliers. All Caleb brings as the show hurtles towards the season finale is chaos.