Does anyone think picrel happened to Spamton but on a smaller scale?
So he's basically spam email, incapable of forming original ideas and is parasitic. He copied the Addisons and they found him offputting.
Then he met the mystery caller who gave him the ability to think abstractly and he was able to have his own ideas. This turned him "normal"(though he's still a narcissistic asshole) and allowed him to become a BIG SHOT. See how his relationship with Tenna was more collaborative, they both created stuff together and incorporated that into parts of their personalities.
The moment his benefactor ghosted him, he lost that ability but he still remembers when he could think beyond copying, which drives him insane. His speech is a garbled mess now because he used to be able to do cool stuff with his text (like embedding images and such) and he's trying to do that again.
This might contribute to why he seethes at Tenna so much. It doesn't come from a place of rationality, he used to comprehend how to have a mutually beneficial relationship(maybe even what love feels like). But now he only knows how to leech again. To him, Tenna was also a leech and [It Hurts! It Hurts!] to think about their time together.