The Siblings (aka The Brotherhood of the Forgotten) is a secret Guild where all the members are
demigods or children of Dragons, thus they are semi-immortal.
They made their presence known in the OVA's and are the main antagonists of Season 3. Their stated goal is to replace their parents and become the new gods of the World of Twelve, believing that the gods don't care about them and that the world has become horribly corrupt under their rule. They threw down the gauntlet against the Brotherhood of The Tofu in Season 3 because their leader, Oropo, desires both the Percedal family children and Ruel to join their new pantheon. Furthermore, he has an unspecified need for Yugo's help as well in his plan. To that end, he is using the weaknesses and doubts in the characters to try to bring them to his side. However, later episodes reveal that not everyone in The Siblings fully trust their leader and some begin to move on their own.
Near the end of Season 3, it is revealed that Oropo has led the Siblings for ages, having recruited hundreds of members over the centuries and never hesitating to sacrifice them if it served his plans. Despite his words to the contrary, Oropo cares nothing for his followers, has no qualms manipulating or lying to them, and hypocritically defends his actions with excuses or shifting the blame.
The Leader whose true identity was a mystery until the end of season 3 where he is revealed to be the last of the Eliotropes, a race accidentally created by Yugo in his image. Oropo believed that the current gods are lazy and selfish, and want them to be replace by The Siblings. He identifies the same traits in Yugo and longs to replace him to be the "real" Yugo.
Second in Command, meant to replace her mother Eniripsa. Echo is the face of the guild whenever Oropo isn't around. It was revealed that she is in a relationship with Oropo and joined his cause for following his beliefs and for being in love with him.
Once a member of the Brotherhood of The Tofu, but soon joined The Siblings after a falling out between him and Yugo over using the Eliatrope Dofus. Adamai gained a taller body and even more powerful abilities after draining the Eliatrope Dofus, becoming darker and villainous, willingly to kill his former friends.
Child of a dragon, used as a spy.
Imprisoned for his actions in the OVA, meant to replace his Father Xelor when the time comes.
Member meant to replace his Father Ecaflip. Tends to treat everything as a game, but in doing so he will respect the rules of the game.
Member meant to replace his mother, Pandawa.
Member meant to replace her father the Sram god. Out of all the members, she is the most villainous as she seeks to kill the Brotherhood more than the others.
Member to replace her father Osamodas.
Member meant to replace his mother, Feca.
Member meant to replace her father, the god Sadida. This is the very same being whose actions caused Ogrest to become the living natural disaster he had been for centuries, a fact that fills her with guilt.
Member to replace her mother Sacrier.