[X] "It's too soon to try to plan around having to deal with Mab on top of the rest of this mess. Why don't we just focus on stopping the necromancer plot for now, and play the rest by ear as the situation develops? I know that's probably not how you normally do things, but it's been working for me so far." And should we need to knock Harry out before he can summon Mab, we can make that decision if and when it becomes necessary.
[X] "I can't hand someone to Mab Harry. Not someone who got away. I know you are stuck in the deal you made, but I can't be part of that. Lydia, if you want to stick with Harry, fine, but I'm going after Katrina."
[X] Then you will do exactly that.
-[X] What you don't tell him that he won't be able to make a summoning circle anytime soon with you attacking him to knock him out
-[X] He can tell Mab once Lydia and her Dad got away