Pepi is a poor boy who became Homer's little brother.
History
When Bart joins the Bigger Brother program and is assigned to Tom. In revenge, Homer signs up as well and gets Pepi. As Homer is his big brother, he learns nonsensical things, such as that whales are not mammals. As Homer and Tom get into a fight, Homer is sent to hospital, leaving Pepi without a bigger brother. Bart sees that Pepi is more deserving of Tom than him, so he pairs them up, and they walk off in the sunset.
