If The Walking Dead had gone with its original plan for Shane (Jon Bernthal), the character would have been killed off much earlier in the show. Shane lasted almost two full seasons before being killed off in the penultimate episode of season 2, shortly before the group had to leave the Greene family farm due to a zombie horde descending upon them.
Shane clashed with Rick (Andrew Lincoln) over his leadership nearly the entire time they traveled together. It was clear that something would have to be done about Shane early in season 2 when he ruthlessly sacrificed Otis (Pruitt Taylor Vince) to save himself from the zombies. As the season went on, Shane became more violent and troublesome, resulting in growing tensions between him and the other members of the group. Later, Shane murdered their prisoner, Randall (Michael Zegen), even though it was agreed that he should be spared. Shane pretended Randall escaped and used this opportunity to lure Rick into the woods, where Rick killed Shane in self-defense; Shane’s zombified body then being put down by Carl (Chandler Riggs).
Walking Dead creator Robert Kirkman has confirmed that Shane’s death would have happened much earlier in the timeline of events if season 1 wasn’t so short. AMC only ordered a six-episode first season, as opposed to a 13-episode season, so this of course affected the structure of the story [via TVLine]. If they had a longer season, they would have killed Shane at the end of season 1 and before they reached the farm in season 2. The trajectory of his story would have been similar to how Shane’s arc in the comic books ended.
In the comics, Rick and Shane’s feud escalated a lot faster than it did in the show. After Lori took Rick’s side in an argument, Shane lost his temper and ran into the woods. When Rick chased after him, Shane made his move; but before he could kill Rick, he was shot by Carl. By extending this storyline to The Walking Dead season 2, the TV version dragged it out a bit longer and provided more conflicts for Shane and the other people in the group, including Dale (Jeffrey DeMunn), Carol (Melissa McBride), and Daryl (Norman Reedus).
So much on The Walking Dead never would have happened if the series had killed him in season 1, which is a fact that’s been pointed out by Kirkman. A significant portion of Shane’s story was related directly to events that took place on the farm. The incidents with Otis and Randall could possibly have worked with different characters and a different location in an extended season 1, but the same can’t be said for the situation with Carol’s daughter, Sophie (Madison Lintz), whose disappearance was a major plot point in season 2. Shane was an obstacle here, as he was more opposed to staying and looking for Sophie than anyone else.
Despite being Rick’s best friend, Shane managed to be a thorn in his side for two seasons. And since he contributed much to the drama that happened on the farm, it’s hard to imagine The Walking Dead season 2 without him.