teacosee
Kai is left behind when the other ninja enter the Never-Realm, with his absence of powers persuading them that he is not strong enough to come with them.
Without their protectors, Ninjago descends into ruins - the police become crooked, and the citizens fall into a state of panic.
So Kai forms a team. They protect the people of the city, but in the end they break more bones then they mend.
And it might turn him just a little bit-
Corrupted...
This was inspired of a Tumblr post, but I can't find it anymore, so I don't know the name of the creator! But HUGE credit to whoever came up with it, it was an amazing idea!