"I'm not here for you to be fixing mistakes. You made the mistake in the first place, arr! That leaves the mistake fixing to me..."
-Rockhopper's last words to Ninja before killing him
Captain Rockhopper first appeared in the episode The Chase, observing the island from the deck of his ship, the Migrator. He then declared that, due to the Tuba Gang inability to bring him the stuff, he would be invading the island, and he rallied The Mascots to prepare for the invasion.
In The Hunter, Rockhopper commenced the invasion and scaled the Mountain Top, which was occupied by Ninja. He and a few Nachos ambushed Ninja, who begged the captain for mercy. Rockhopper dismissed Ninja's pleas and chastised him for not being able to keep things under control. Rockhopper then had the Nachos throw Ninja off the mountain to send the other Moderators "a pretty clear message".
"Rememeber what you´ve done here. Remember that you deserve it"
-The Nacho Gang Leader last words against Rockhopper
In The Wasteland, Rockhopper was seen trying to sleep, but wound up suffering from symptoms of withdrawal from the mushroom bags. He angrily cursed out the Tuba Gang, which prompted the Nacho Gang Leader to inform him that the Tuba Gang was dead. The Nacho Gang Leader warned Rockhopper that his operation was going to fail, but Rockhopper scoffed and reminded the Nacho Gang Leader how the Nachos - and many other penguins - still blindly worship the Mascots. But the Nacho Gang Leader still insisted that Rockhopper was going to fail miserably and told him about how one penguin was taking down all the gangs, but refused to tell Rockhopper the penguin's name. So, Rockhopper had The Freak torture and then kill the Nacho Gang Leader with hot sauce while the rest of the Nachos were forced to watch. Before his death, the Nacho Gang Leader finally told Rockhopper that the penguin's name was Lil Jeffy.
Rockhopper is a ruthless, vicious leader who rules with fear and has no problem with disposing of anyone who fails or opposes him. However, unlike most of the crimelords on the island, Rockhopper still has some concern for the island. He sometimes opens up to his peers about his old life as a Mascot, and has even admitted to wanting to restore the island back to its former glory someday.
Rockhopper is a red penguin fully dressed in pirate apparel. He has bushy eyebrows and a big black beard.
Rockhopper appears to be dominant over the other mascots. He has apparently made himself their leader.
Sometime before the events of the series, Rockhopper had made an alliance with the Tuba Gang. In this arrangement, the Tuba Gang was tasked with supplying Rockhopper with Mushroom Bags, and in exchange Rockhopper and his crew wouldn't invade the island. However, after the Tuba Gang failed to deliver due to being killed by Lil Jeffy, Rockhopper angrily declared the Tuba Gang to be useless and decided to invade the island.
The Freak is the Rockhopper's executioner. He often lets the Freak torture his prisoners, but gets annoyed when the Freak overdoes it with his theatrical antics.
Rockhopper has taken over the Nachos and forced them to work for him, much like how the Tuba Gang Leader did with the Purple Republic. Although their leader despises Rockhopper, the rest of the Nachos don't seem to mind working for the pernicious pirate.