What a difference a season makes. When Showtime’s drama “Shameless” returns for a second season in January, the Gallaghers have shed their winter coats in exchange for cut-off shorts and tank tops. Yes, it’s summertime and the living is sleazy — at least for Frank (William H. Macy), it is. For the rest of the family, the rise in temperature seems to be a recipe for recklessness, as Fiona (Emmy Rossum) sleeps around in an attempt to get over Steve (Justin Chatwin), and the kids go absolutely bonkers without the restraints of school. Below, the show’s cast previews what lies ahead in Season 2 (Sunday, Jan. 8 at 9/8c).