Abe Simpson throwing Homer under the bus for the attempted murder of Mr. Burns.
Also possibly Abe Simpson shooting down a German airplane. If he actually did it. (In 1994, not during WW2)
Edit: Oh and I guess Abe Simpson cheating on his fiancé, getting the side woman pregnant, giving up the baby, and keeping everything secret from Homer and his other son until he thought he was on his deathbed.
And then when Abe Simpson told young Homer his mother was dead and never came clean until she showed up again.
Man, Abe sucks. It’s a wonder Homer didn’t stick him in that crooked home he saw on 60 Minutes.
Homer definitely fucked with multiple timeline branches in one of the earlier Treehouse of Horror episodes when he has the time machine toaster. The ecological impact of wiping out the dinosaurs in one alone alone is pretty significant.