The Oni Twins are two powerful demons created by the queen of hell. They were to be servants for her. Origanally they were to be one demon, but due to an accident, they became twins. Ironically, this same accident cause Blue Oni to get the fire powers and Red Oni to get this ice powers, contrary belief.
For the longest time they were loyal to the Queen, but secretly, they wanted her power. They knew they were powerful enough to take her down together, so they plotted to take her down. But she found out, and when she did, she was furious. She called the Oni's to her and punished them for their treason by cursing them into small imp forms, where they were significantly less powerful.
They Oni's argued about who's fault it was that she found out, and eventually split up.
Blue oni is the calmer, smarter one of the two. Finally fed up with his brother and his shenanigans, he left to find away to rid of, get around the curse. That's when he met up with The Shadow Lord. The Shadow Lord proposed that if they worked together to get the Goddess Blades, the blades would give both of them all the power they would desire. But of course, and imp can't leave the underworld, so then The Shadow Lord told Blue to go possess a child on earth. A child would be easier to train the body of and more useful once it finally dies.
Blue Oni then found Emette, a child who had just lost his parents, peoples trust and all hope for the future. A perfect candidate. It helped that the boy looked a bit like him, so it wouldn't be a big change once he took the body over. He met up with Emette in the basement of the orphanage he stayed in and convinced him that, if Emette agreed to give Oni his body, he would show him how to get his parents back and make sure no one he cares about ever gets hurt again. Desperate, Emette wholeheartedly agreed.
Afterwards, both of them were introduced to Sherry. She was to be their guide and Emette's partial mentor while they tried to get the blades.
Emette never made a pact with Blue oni, being as stubborn as he is. As such, Blue Oni tends to pick on Emette a lot. He will often say things the lowers Emette's confidence so that he will not rebel. But when Emette does rebel, he will either torture him either physically or emotionally, or he will just completely take over his body. When Oni takes over Emette's body, the whites of Emette's eyes darken and horns, claws and a tail appear. Emette usually has Oni's pointed ears and teeth naturally due to the possession.
Blue Oni has two powers. One is the previously mentions power to control fire. The other is the power to control souless demons. Both of the twin possess this ability but which ones they can summon differ. Oni has an easier time summoning souless with mental based abilities.
Red oni is much more easy going than his brother. After getting tired of his brother blaming the cure on him, he left and went on his own for a while. Unlike his brother, Red was not as anxious to rid of his imp form, but when he heard about what Oni was doing with the Shadow Lord, he had to get in on the fun as well. While he didn't team up with any higher power, he did make a deal with an mortal teen named Dallas. Dallas had recently lost a good friend to a petty gang, and Red promised he'd help him get revenge.
Unlike Blue Oni and Emette, Dallas made a pact with Red Oni. Pacts combine a human and they're demon possesser's souls in order to accomplish a single goal. This not only created a strong bond between him and Red, but allows him far more control over his powers than Emette could. As well, Dallas can go full demon mode on his own and certainly far quicker than what Emette can do. Making a pact with a demon also allows Dallas to respawn after dying under the right conditions, ie, dying while Red is still inside of him. If he is to die after the demon has left, it's game over.
Like Blue Oni, Red has two powers of his own. One is the ice power and the other, of course, is the power to control souless. He has an easier time controling the brutish, strong souless.
- 'Oni' means 'demon' in japanese while 'akuma' means 'devil'.
- It is said that when the Queen of Hell created the twins, they were origanally supposed to have powers more appropriet with their colors, (ex; Blue oni = ice, Red oni = fire) but the process was corrupted, swapping the two.