Regarding the support Seph is going to need -- Jade is definitely not going to coddle him, but he does know what it's like crossing the line into doing bad things, and thanks to canon events he has a very "screw destiny" mentality about it.

Basically, he's going to hold Seph accountable if he turns evil, but also support him if he decides to fight it. It's all about free will and personal responsibility with him.