From MC's Perspective:
I'm looking at my senior brother. I can feel he is hiding his real intentions. I don't know what will happen in the future. If he wants to kill me, then I won't have any other choice but to retaliate as well.
Ed Conrad shows a neutral expression on the outside. But inside, he is angry because he has realized right now that his junior brother has found out his true face.
It would be difficult to take any action in the future. Thinking about it, Ed Conrad's mood worsens. Surely he can't take action by himself because of Master Austin.
He thinks that Master Austin would find out easily as long as there is a small clue. Ed Conrad has decided to target Zack Lockwood hereafter.
Even if he wants to do anything, he would seek outside help, like the Black Flame Palace members. The duo then retreated without attacking Zack Lockwood.