Um

I doubt Serini would betray the Order to Xykon. She's going through a lot of trouble to stop *anyone* getting harmed by Xykon, and if the Order goes to fight Xykon Serini likely won't even be in the room.

Unless your logic train is 'the order is gud and Serini is attacking them so Serini is def bad' which is going to be hard to argue against.