I like to think that the monster in the cage is actually Pentagon's master. Like he's ninja sneaking into the cage room during his off time just to pay homage to whatever the hell it is. It can't talk, it can only emit psychic waves of cero miedo. Or maybe after he saw it he realized nothing is scarier than whoever his master is. I'm probably wrong but I don't care. The more ridiculous the better.
I think if you want to turn Fenix heel this season then this is how I'd explain it. He lost 999 lives in Grave Consequences so in order to preserve his final life he'll start being evil and take every advantage he can to live, and become the champion I guess. I still have no idea about Katrina's true motives other than she's some sort of shadow specter who wants to lick losers. Bring back Mil and create a Katrina faction.