A demon twins au that I have been thinking about for a while

Danyal and Damian find out that Ra's intends to have them fight to death for the title of heir so they decide to have a duel during a mission and fake the loosers death. This way the stronger one gets to have the title, just like how Ra's wanted, but they wouldn't have to kill eachother. They don't want to disobey their grandfather, but surely this would have the same result without unneeded tragedy.

Damian wins so he claims that he killed Danny for being weak. They promised to never try to contact eachother so the league would not find out. They wouldn't know eachothers situations from the outside after all. They couldn't risk it. After years Danny knows that Damian is Robin in Gotham but doesn't know if hes out of the league or not. Damian has no idea where Danny is and never told the batfam.

Then some magican tries to kill Robin by summoning his dead brother to exact revenge. Damian is sure that the summoning will not work because Danny should be alive and well, only to be devastated to see the ghost of his brother appear from the summoning circle.

Additional thoughts. They have their own code made up of sign, gestures, and body language they can use to communicate hidden meanings behind their words or just completely different things. They have mastered the art of having a private conversation while to outsiders it looks like they're verbally ripping eachother to shreds. I can see them using this to figure out how to deal with the situation while keeping up the ruse. Maybe the bats come in and deal with the mage while Damian and Danny are "arguing" and "antagonizing" each other. While in reality Damian is convincing Danny that the bats can be trusted and Danny is debating if the risk of revealing everything is worth it, and if its already too late not to. And when they agree on dropping the act the bats get whiplash from the arguing turning into a tight hug in a second.