WMG / Sabrina: The Animated Series

Pi is actually a female pop star disguised as a boy who wanted to escape the constant adoration of his/her fans and live a peaceful life.
Get ready for the weirdest theory you've ever heard.

OK, so anyone can see that Pi is strange. He's a weird kid with long hair who is obsessed with the occult. Then in Sabrina's Secret Life, he's just...gone. Well here's your explanation. Pi is a Merperson. Okay, sounds crazy but think about it. His voice sounds odd (almost like a surfer), he has long hair, he's obsessed with magic... sounds a lot like Ariel (minus the voice though), who wanted to know everything about the human world. Pi is a brainiac who studies hard and researches the occult because he wants to know everything, so he made a deal with the Witches Council to have legs for a while and study humans, but his time on land was limited so when he turned thirteen he had to return to the sea.

Pi is a girl and the one whom HARVEY has a crush on but Sabrina views her as a boy and we see her through Sabrina's eyes because she doesn't want another love rival like Gem.
  • If you look at Pi's mannerisms he's very ladylike especially the way he sits and walks.

Pi is somehow or in some way acquainted with Mr. Crocker and will someday become like him. (or he IS him)
  • Pi is from the Other World and that's why he doesn't show his eyes. They're buttons.

Hilda and Salem were lovers once when he was a human.
From what we've seen Hilda really gets around and Salem would have wanted her at some point.

Pi is actually a trans boy and who's gay AND he has a crush on Harvey.
What's more Harvey (and Chloe) know everything and Harvey feels the same way about Pi. Too bad they won't tell the other one how they feel (for now)... Sabrina is out of the loop however and since we see things from her POV we supposedly know nothing as well. But we do.
  • Or Pi could be a cis boy who is in touch with his feminine side. He still could be gay for Harvey though.

Neither Sabrina or Gem actually have feelings for Harvey.
It's just part of their rivalry. They both think the other one wants him to they fight. Actually they don't really care that much for him.
  • Well then, Pi gets Harvey all for himself! Yay!