Okay, so I finished watching the finale of Alternates, and after processing the events for a few hours (And losing sleep) I felt the need to yap. Specifically about the implications of what happened to Kaitlyn, and what it teaches us about what the alternates actually ARE.
SPOILERS AND THOUGHTS UNDER HERE!
We see Kaitlyn being tormented in her mind, by the Pierce alternate who infected her. Something I found interesting was that Kaitlyn clearly saw him as a tormenter, who only sought to scare her, yet he was trying to WARN her. He said "Cut it off" clearly referring to her infection, and when it spread too much, we saw what happened. It seems like the Pierce in Kaitlyn's nightmares, didn't want her to become an alternate, and tried to warn her of what she needed to do to prevent that. He was trying to HELP.
This has caused me to wonder if the Pierce Head Spider was actually Pierce at one point, but he was taken over by the infection. We learned that when someone is wounded by an alternate, they can get an infection that slowly takes over them, turning them into another alternate. Perhaps when someone is killed by an alternate, their corpse becomes infected, and the person they were before is trapped in this twisted version of themselves, unable to know peace.
We also learned that the alternates appear to have some kind of hive-mind, allowing more powerful alternates to control the others. As in the final battle Kaitlyn, despite being an alternate, is still trying to protect her friends, but the big alternate in the crater tries to control her. She resists, with verbal encouragement from Aphmau and Travis, but the control is hard to fight, and for a lot of the battle she is frozen in place.
I now have a theory, that the Pierce who haunted Kaitlyn, was the real Pierce, reaching out through the psychic connection between alternates, in an attempt to save her from becoming like him. Warning her to cut of the infected leg before it's too late. Unfortunately, Kaitlyn doesn't listen, believing him to be a nightmarish hallucination who only seeks to torment her further. As a result, the infection consumes her, like it did to Pierce.
Another thing shown in this episode, was that alternates who were once human are in a constant state of agony. Which is tragic and horrifying, and makes me wonder if there are more alternates like Kaitlyn, who aren't actually evil, but are in so much pain they can barely control themselves... This also shows Kaitlyn's strength of will, considering she maintained control of herself in this state, and barely wavered when the big alternate tried to take over.
RIP Kaitlyn, you fought until the end, you deserved so much better.