Patrick showed up in the season 3 finale, and stayed every episode of season 4. He even was in the first 3 of season 5. He was a big part of the show during that time. It's weird they didn't put him in the opening credits. He even appeared in photo shoots with the cast in season 4. Probably from day 1 of them. For them to do that and leave him out of the opening credits was stupid. They put him in all the photo shoots, so he should have been in the intro. Also, he didn't miss one episode from the time he showed up until season 4 ended. He was always there. The same goes for Rena Sofer. They featured her in cast photos as well. She didn't miss one episode after she showed up and was a big part of the final season but didn't get in the opening. A lot of fans even thought they should have been in the intro.