context: In the Minoan Bronze Age, a shadow loomed over the village of Thena. Every three years, under King Deucalion's order, eight youths are taken from the village to the capital of the Minos' Empire. There, they are placed in an underground labyrinth to be sacrifices to the Minotaur, the Minoan god.
  Theo, son of Cyrnan, the village chieftain, is haunted by the loss of his love, Fion, in an earlier sacrifice. A leprous prophetess tells him that Fion is still alive in the labyrinth. Against his father's wishes, he replaces one of the sacrifices and is taken to the Minos Empire capitol. Other captives are Danu (Theo's best friend), Morna (Danu's love interest), Tyro (who initially resents Theo because of his standing), Didi (Tyro's love interest), Vena, Ziko and Nan.
  After the group are dropped into the labyrinth, the Minotaur immediately begins hunting them and kills Nan. The survivors are approached by Queen Raphaella, Deucalion's sister and unwilling lover, who offers them a way out. Vena does not believe her, and when she attempts to leave the group, the Minotaur impales her with its horn. The rest of the group evade the Minotaur and, led by Raphaella, they get to a chamber at the center of the labyrinth. There, the monster lies asleep on its victims's remains, and a heavy wooden door leads out of the labyrinth. Raphaella had arranged for her servant Ramaya to open the door from the other side, but Deucalion catches the servant and has her executed. Desperate, the group attempt to break down the door. The noise wakes the Minotaur, which kills Ziko and splits up the group.
  Theo, Danu, and Morna encounter Turag, a villager from a previous offering. Turag has managed to elude the Minotaur thus far, but has become slightly insane over the years. Looking at the map of the labyrinth Turag has drawn, Theo learns of Fion's supposed location and goes off alone to find her. However, he eventually discovers her corpse, and realizes that she was poisoned by an underground gas deposit. Meanwhile, Tyro and Didi find one of the holes that they were dropped through. Tyro climbs up and reaches down to pull up Didi. As the Minotaur arrives, Didi panics, loses her grip and falls onto one of its horns. The Minotaur then corners Danu and Morna, and Danu sacrifices himself to save his lover.
  Raphaella reaches Theo again and explains the Minotaur's origin. Her mother gave herself to bestiality to create a living god, and gave birth to the Minotaur. As the monster grew, so did its appetite, culminating in it murdering Deucalion's brother. Theo's village was blamed for the prince's death, resulting in the human sacrifices to appease the Minotaur while ensuring Minos' own survival. Raphaella sent the leper to find someone in the village capable of killing the Minotaur, and thus the leper lied to Theo about Fion's survival to make him face the beast.
  Theo discovers the underground natural gas vent in the labyrinth. When the Minotaur prepares to kill Theo, Tyro sacrifices himself to distract it. Theo tempts the Minotaur into attacking him, and lures it towards the gas vent. He then creates a spark with Fion's amulet. The gas ignites, engulfing part of the labyrinth, while Theo and Raphaella survives by diving into a pond of water. They emerge from the water as the flames die out, and find the beast still alive and enraged. As the Minotaur charges at him, Theo takes the monster's horn which was broken earlier, and impales it in the mouth. It keeps charging forward, and collides with a rock which drives the horn through its head, finally killing it.
  Theo and Raphaella reunite with Morna and Turag and leave the collapsing labyrinth. On the surface, they find out that the explosion also collapsed the palace and fatally wounded Deucalion. Raphaella smothers him to death, ending the cycle of fanaticism. The Minos' empire ends with the deaths of the Minotaur and Deucalion; Theo becomes a legend for killing the monster.
question: How are King Deucalion and Queen Raphaella related in the movie?
answer: brother and sister