It was a teenage boy, who Bobby apparently recognized. Because he stood up (in Brandon's body) and said "Mike, what are you doing here?"
Mike paused in mid-step and looked at the older man. "Do I know you?" Then he looked over at who he thought was Bobby (but was actually Abigail). "Dude, I thought we were gonna go ..."
Before he could finish his sentence, though, someone grabbed his arm and pulled him back towards the front entrance.
And the moment the person touched him, a purple glow began to engulf his body, not unlike the purple light that was in the café before everyone in it switched bodies. And when the light was gone, Mike was different. Just like what happened with Melissa and Duke, Mike had become like the person who touched him.
But who touched Mike?