Originally Posted by
MichaelC
Cartman actually saved Kyle during the smug incident. It's heavily implied that Cartman enjoys his rivalry with Kyle. He's basically got a Joker type fixation on Kyle. Everyone around Kyle dies, though, especially if that person is important to Kyle winning in some way. Like if Kyle winning some argument is dependent on someone living at least another week, that person is dead as dirt.
Indeed, he'd likely kill that person, and then talk to Kyle in a way that, in Cartman's mind, very very subtly implies that he did it. Cartman would be confident that Kyle wouldn't pick up on his brilliant, super-subtle implication, and that, even if Kyle figures out he's the killer, that he won't possibly guess that the weapon was a death-note.
Kyle would then immediately respond with "oh my god, Cartman's got a fucking death note!"
Cartman would immediately become panicked and defensive, not realizing that he had been far less subtle in his implications than he intended. Probably responding with a panicked "nuh uh!"