Have the writers forgotten that they showed us lockes daddy behind the door. What happened to him and wtfh is he doing on the island. Where's cooper now?
Cooper bit Lockes hand, hence the bandage on his hand, and Locke went with the others to the ruins and Ben asked Locke to kill Cooper to show that he was special or sumthing like that.
Locke couldn't do it and went to get sawyer because he somehow knew cooper was the real sawyer and also knew that sawyer wanted revenge.
sawyer killed cooper and was told some info by Cooper about Locke