Ritchie is the reincarnation of Riccaro.
Because Riccaro was split from Set's soul, Ritchie is still connected to Set.
The reason why the father doesn't want Ritchie's to take the thrown is because he knows of Ritchie being connected to Set. He purposely kept Ritchie away from anything that could relate to Set. Soren does have Set's/Riccaro's staff and artifacts locked away inside the castle.
The mother was having trouble conceiving kids so Soren made a deal with a god/goddess of reincarnation and Set. Set was trying to be better and threatened to kill Soren multiple times. The mother remains unaware of this.
Now Riccaro died, well almost died before achieving godhood. Before Riccaro fully died the god/goddess took his soul and stored it, away for years. Now because he never fully died, his memories can come back and so can his not humanness. He will be able to turn into his red and galaxy form, however now he can look human whenever he wants. (He will still have the lines)
Now you can decide what happened and how. You can either have the parents conceive Brandon at the same time they recieved Ritchie's soul or them already be pregnant and lost one of them, but the god/goddess gave them Ritchie's soul so they wouldn't lose the kid. Or you can have Brandon be a reincarnation of Lychee.
The eye Brandon has helps keep Ritchie separated from his old life and keeps Set away.
The god/goddess didn't fully trusted Set so they set up a protection around everyone involved in Ritchie's life.
