Is it sibling rivalry if it's just one-sided?

So in recent weeks, we've started to notice how little Jeremiah thinks of his counterpart, Davis.

Example #1

Jeremiah: "Mommy, I want to go to the store and get green paint so that I can paint myself all green and be the grinch. I also want to get reindeer antlers so Davis can be the dog.

Example #2

Jeremiah: "Davis, you are a good penguin because you walk funny and you are fat."

Davis: "I'm not fat."

Jeremiah: "No, you have a fat little belly, like a little penguin."

Example #3

Jeremiah: "We can play Wizard of Oz. I will be the Lion and Davis can be the scarecrow. He has no brain."