Red is a Dark Spawn Lord and is the chief anatagonist of All Dogs Go To Heaven 2 - a powerful demon who was aided by Carface his plan was to use the magical Horn Of Gabriel to literally pull all the dogs from Heaven and imprison them in an island prison.
To this end, he tricked Charlie into aiding him via creating magical-collars and forcing him into a deal: this climaxed in the demon managing to actually get the horn and he began to imprison the inhabitants of Heaven and growing into a monster of seemingly apocalyptic proportions, causing the sea itself to start to rise around the island in a massive whirlpool.
However, Charlie and his friends decide to fight back, resulting in a battle that ended with Charlie blowing the horn: reversing the evil spell.
Red, who had already been weakened by the battle, was ultimately dragged back to Hell.
Role in the series
As it turns out, Red had been one of the original Dark Spawn lords under the command of Chernabog billions of years ago. He was also one of the few demons who remained loyal to the dark lord even after his imprisonment in Bald Mountain. Currently, he and his minion, Belladonna, have found a way to escape Hell, but have not yet appeared in the Spongebob adventures series to plague Spongebob's life, but he has a presence in the Banidshed Realms as he is not a cat, but actually an evil cat-like entity like Mirage. Red's relationship with Carface has, on the other hand, been ripped off into Fagin and Ratigan's relationship because Scroopfan thought of the idea that Ratigan ends up in a simuler situation with Carface, a notorious criminal mastermind becomes a second banana to a demonic villian, would be interesting to see again. If Red does appear in the series, he will have to have his skeletal cat mnions be replaced with the puppy goblins from the first film, or even the dog-like imps under Belladonna's command. This is because not only does Scroopfan hate evil cats and founded a rule of anti-catism against it, but he feels the idea of dogs only go to heaven, and that cats only go to hell seems a bit racist, hence why Red was replaced with Fagin in the very first place. However, he still has a role in the series to where he is not a cat according to the no-cat-villains rule, as he created Freddy Fried Khicken as a way to haunt Shenzi, Banzai, and Ed for being related to the Pure Hyenas, one of the Darkspawn's old enemies.