Sayid: So, what killed Eko?
Locke: Folks back at the beach call it The Monster. I don't really have a name for it. You don't believe in monsters.
Sayid: I believe in what I can see ... but obviously you have. So why don't you tell me what you think it is?
Locke: Might be what brought us here.
Sayid: So you believe that this monster decided that Eko was supposed to die?
Locke: I believe Eko died for a reason. I just don't know what it is yet.