I've already dealt with this. Every single person in town is mind controlled. That's explicit. So Pietro not acting like Pietro would be normal in this setting - he specifically said he is acting the way Wanda wants him to act in the Halloween episode. And the Agnes scene showed her magic on Pietro when he first comes to the door at Wanda's house - why would Mephisto need any help from Agnes, or be controlled by Agnes? And if the fly on the wall, which is an explicit reference to Mephisto, is indeed Mephisto as was the way he was introduced in the comics, he isn't likely to also be Pietro at the same time. As to your comments on Monica, that doesn't explain the multiple versions of Monica was saw, but instead represents her internal dialogue that allows her to overcome them. But only 2 eps left, so we'll see.