What happened to Tom Hardy's character again?
Alfie Solomons, a mainstay of Seasons 2-4, went from series villain to friend to villain once again when he struck a deal with Luca Changretta to spirit Luca's boys into Small Heath to take down the entire Shelby family -- a deal that, fortunately for Tommy and unfortunately for Alfie, didn't result in the Shelbys being wiped from the face of the earth. Tommy, Arthur, Michael, and their Aunt Polly survived the plot, and, given that everything in this world revolves around honor and deals and equal distribution of grief, Tommy had no choice but to try to shoot Alfie dead.
They met on the beach outside the seaside town of Margate, Alfie holding the leash of a nice, large dog, and Alfie confessed to everything. He also told Tommy that he was dying anyway from cancer -- which is why he spent the entire season covered in scabs and looking overall pretty gross. Tommy listened, and then shot him in the face and left him for dead. (The dog is fine, though.)