Pietro wasn't waiting for any plan. He didn't even hear Rogue speak. The second he heard his father's words and saw who he had dragged along with him, he was gone.
Outside he stopped short of grabbing distance from Magneto, muscles tense, and eyes fierce with a burning glare. And then he was silent. Which was when you knew he was really dangerously mad. There was no where on Earth his father was going to be able to hide from him after this, no matter what happened.