When the zombie outbreak began, Rick Grimes was still lying comatose in hospital. Shane was uncertain what to do for his friend and time was running short, with zombies invading the hospital and soldiers gunning down living patients as well as the undead. Unable to wake Rick and fearing for the lives of Rick's wife and son, Shane blocked off the door to Rick's room with a guerney and made his escape from the hospital.
Shane took Lori and Carl Grimes out of Kings County and they headed toward Atlanta where the army had apparently set up a safe zone for survivors of the zombie pandemic. However, Atlanta turned out to be a dead end, already overrun with walkers and being bombed by the military. Shane later took Lori and Carl to an abandoned quarry some distance outside of Atlanta where a number of survivors had flocked and established a camp. For the time being, they were safe.
Shane established himself as the leader of the group, possessing the most proficiency with weapons and necessary leadership and survival skills. During this time, he and Lori became intimate since both believed Rick to be dead and Shane had long been attracted to Lori. He became a surrogate father to Carl and the boy still held him in high esteem after his real father turned up alive and well.
After Rick joined the camp, he and Lori quickly re-established their former relationship and Rick also demonstrates remarkable leadership qualities, earning the respect of the other survivors who start looking to him for support. While initially glad that Rick is still alive, Shane soon begins to resent him for walking back into his life and taking Lori and Carl away from him. He hides his jealousy from the others, but his feelings begin to interfere with his ability to lead and protect the group.
In the second season, Shane begins to undergo a significant personality change and completely abandons whatever morals he had. He continues hiding his resentment of Rick, letting it fester over time until it turns into outright hatred. He becomes fixated on protecting Lori and Carl at whatever the cost, even at the expense of the lives of the other survivors. He becomes increasingly hostile towards Dale, continues making advances on Lori and even goes so far as to sacrifice Otis to the walkers in order to save Carl after the boy is wounded.
It is later revealed that Lori is pregnant and Shane is convinced that the baby is his, but Lori tells him that it can't be his and that it is Rick's. Lori tries to make Shane see that the two of them are never going to be together, but this only serves to fuel Shane's emotional instability.
DeathEditIn the episode "Better Angels", Shane - having let his jealousy of Rick get the better of him - devises a plan to get rid of his old friend once and for all. He chooses his moment to act when no one is watching him and he frees Randall from Hershel's barn, taking him into the woods and pretending to want to side with his group. As the two start walking, Shane leads Randall behind a tree and snaps his neck off-screen. He then bashes his own face against a tree to make it appear to the others that Randall attacked him.
That night, Shane, Rick, Daryl and Glenn search the woods for Randall and Shane suggests that they split up. Shane leads Rick out into an empty field where he intends to kill him, but Rick is aware of Shane's scheme and tells him that no one will believe his cover story if he goes back to the farm alone. Bitter and angry, Shane tells Rick that he should never have come back, that Lori and Carl would have been better off just having Shane to protect them. He then tells Rick to raise his gun as he raises his own, but Rick refuses, stating that Shane will have to kill an unarmed man in cold blood.
Rick makes it seem as though he's handing Shane his weapon. Once his gun is in Shane's hand, Rick pulls out his knife and stabs Shane in his heart, screaming that Shane is to blame for bringing the two of them to this. Shane then dies in his arms. As Rick tries to cope with what just happened, Carl appears, shocked to see Shane dead. The boy raises his own gun seemingly to Rick, but he is actually aiming at Shane who, despite not being bitten by a walker, has still reanimated. As the zombified Shane is about to bite Rick, Carl pulls the trigger and strikes Shane in the head, killing him for good.