ok completely out there theory time, but someone take a screen shot because if i'm right I'll never stop gloating
none of the main characters will ever fight Jack/SS... because he's on their side
Midnight Crew SS was shown to be an enemy of Lord English, and I think its been shown that LE is behind the game's existence, with Jack always placed under the queens direct rule and he hates it.
also Rose has independently realized that the game is the real enemy and has stopped playing by the rules, and she's probably unaware of Jack at that point
Jack is probably responsible for Bec being earth's "first guardian", ensuring that isn't a malevolent agent of the demon, but a "good dog; best friend"
this is all going to end up with something happening that destroys lord english before he can appear, but to do that they need to destroy the game, which would cause every character to never have existed