I Can't Do It Anymore
Lori had just talked to Shane, apologizing for everything she had to him. Shane had had it. He couldn't stand not having anything anymore. Rick got a wife, a son, and now he's gonna have his son. Rick was doing everything wrong; he wanted to let Randall go, even though he knew was a threat. Shane decided to fix things, to make them for the better.
Shane released Randall and brought him to the woods. He didn't know what he was going to do, but he knew what he wasn't. "I'm sick of this group," he told Randall. "I don't fit in. I wanna be in yours." Randall had quickly agreed, and told Shane how they were a crazy group, and how he would fit right in.
That's what Shane wanted to know. If Randall really were a good guy, and he wasn't like his group, then he would have opted to stay. He knew where they were the entire time, and he was going to lead Shane straight to them. Shane knew how hard it was to kill a good man; he had killed Otis. But he also knew how hard it was to kill an evil man. Or rather how easy it was. The moment Randall confirmed his suspicions, he knew what he was going to do. He went behind him, grabbed his neck, and broke it.
Randall was a threat to his group, and an evil person. He probably touched those girls he had told Daryll about, or at the very least watched. How else would he have known so much about what had happened. Shane threw himself into a tree; he needed to make it look like Randall had escaped and hurt him in the process. He went back to the farm.
Shane was with Rick, while Glenn and Daryll went another way. He knew that Rick would have rather gone with Daryll; Daryll was his new go - to guy. But he knew. Rick knew what he had done, and he wanted to try and talk things through. That was his problem; he always wants to talk, never make the hard choice. He could kill another person, not unless they were an immediate threat.
Shane had his gun aimed at Rick. He hoped things would go right. He didn't want to shoot him, at least not in cold blood. He wanted Rick to pull his gun. But he didn't. He holstered his gun instead. Shane began to taunt him, trying to egg him on. Rick removed his gun and lay it on the ground.
Shane knew he would kill him right then and there. If Rick really did believe that Shane would kill him, and that he was a threat to his family, then he should have left him on that school bus. But instead he risks everything; Lori, Carl, the baby, everything and everyone.
Rick reached for Shane's gun. Shane was going to kill him; he didn't want to, he really didn't. He tried to egg him on, he tried to outright tell him that he was going to kill him and take everything he had. But he wouldn't do it. He was about to pull the trigger when he felt a sharp in his chest. He squeezed the trigger, firing off into the distance. He looked down and saw Rick holding a knife, which he had impaled into his heart. He had done it; he killed him.
Shane looked Rick in the eyes. He was happy he had done it. They both wanted to protect Lori and Carl. They both loved her, despite what Rick said to Shane. Shane knew that whoever lived tonight should be the one to lead the group. He was happy that it was Rick. He didn't want to live with the knowledge that he had killed his best friend, that Carl and Lori would hate him for the rest of their lives, and long after that. He couldn't do it anymore.