Though most of his flashbacks are horrifically bad, I love bb Charlie. Let's talk about him and his episodes! And even Fire + Water has super cute Hurley/Libby bonding!
Poll "The Moth" is the seventh episode of Season 1 of Lost. Charlie struggles with withdrawal symptoms after giving his remaining heroin stash to John Locke. Elsewhere, Sayid sets in motion his plan to isolate the origin of the French distress signal, in the hope that it could provide a means of finding a way off the Island. Flashbacks in this episode center around Charlie's struggles with the temptations involved with being a rock star and also his older brother's massive ego.
"Homecoming" is the fifteenth episode of Season 1 of Lost. The happiness of Claire's return is short-lived as the survivors realize that she is suffering from amnesia. Ethan returns, demanding he get Claire back or he will kill the rest of the group, one by one. Flashbacks in this episode feature Charlie's new romance with Lucy Heatherton.
"Fire + Water" ("Fire Plus Water") is the twelfth episode of Season 2 of Lost and the 37th episode of the series as a whole. Charlie comes to the conclusion that Aaron must be baptized and be "saved", prompting him to recall his past of trying to save his brother. Meanwhile, the first signs of Hurley and Libby's relationship begin to show.
"Greatest Hits" is the twenty-first episode of Season 3 and the seventieth produced hour of the series as a whole. It was originally broadcast on May 16, 2007. When Desmond has another one of his flashes, Charlie is forced to come to terms with the notion that he may have to die to ensure everyone else's rescue. Meanwhile, Jack formulates a plan to combat the Others when they arrive the next day, but complications arise. In flashbacks, Charlie recalls the five best moments in his life to give to Claire before he goes. Charlie says goodbye to Hurley and omg it's so cute.
(summaries from lostpedia)