He first appeared in "Baby on Board". When there was a prom at Alex's high school, after saying it was lame, she did get asked by a boy named Michael. Claire told Alex and him to take a picture of the two, and when she taken, it can be seen that Michael was a little bit effeminate.
In "Yard Sale", he comes over. Claire started to think he's gay, and Mitchell and Cameron confirm her suspicions. Initially, Alex doesn't believe that he was gay, but, finally, they convinced Alex to ask him. This isn't met well, as Michael gets very angry and upset. Later, however, they are seen being intimate again, so maybe they didn't break up definitely.