In 'A Ladder to Heaven', the 12th episode of the sixth season, Cartman drinks Kenny's ashes with some milk, which results in him experiencing several of his friend's memories, while also being possessed by his soul. The second theory is actually extremely similar, but there's a bit more weight to it. South Park just did a thing it hadn't done before The natural conclusion here is that Cartman is aware of Kenny's immortality, simply because he sees things from his perspective (via Redditor freddiemercur圓001).
In 'Succubus', the third episode of season three, Cartman convinces his optometrist to give him an eye transplant, using Kenny's frozen head as the donor. So why is it that Cartman is able to spot what the others are so oblivious to? Well, there are two popular theories, and the first of which concerns him seeing things through Kenny's eyes – literally. And in the season six episode 'Cartmanland', when being sued by Kenny's parents over a fatal amusement park incident, he outright states: 'What, Kenny? He dies all the time!' In the season two episode 'City on the Edge of Forever', he tries to explain to Stan and Kyle that their hooded friend has died numerous times before. As some fans have pointed out over the years, Cartman appears to be the only character, aside from the McCormick parents, who's aware of Kenny's many deaths and subsequent resurrections.
