Many people watch someone from another universe, a 'fictional person' being tortured to death for their entertainment, and there isn't any proof that the characters in, say, Saw, aren't real people somewhere.

Likewise, if you watch fiction where people are happy, there isn't any proof that the existence of a happy character in your fiction isn't associated with a real person somewhere who is suffering.

Thinking about the possibility that there's a suffering person who corresponds to fiction about a suffering fictional character, but not thinking about the possibility that there's a suffering person who corresponds to a happy fictional character, or for that matter the possibility that there's a suffering person (created by a perverse Omega) who comes into existence whenever you eat a slice of pizza is a form of availability bias. It's easier to imagine the former since your mind is processing the concept of suffering at the time, but there's no actual reason to expect that that pair is any more closely connected than any other arbitrary pair.