Donkan

Like, Danny could reincarnate as Darkside and some human son, and Sam and Tucker as children of high members of the Apokolips army

So, when the three of them become 14, they start to gain their memories from their past lives. It gets to a point where, as the three of them have fascinating memories of Earth, they go there with a "we are old enough to start to do missions out of apocalypse, dad", and then they three go to Earth.

The problem is: they, recognized in all the galaxy as the legendary royal trio of Apokolips, traveling in an infiltration ship to Earth, a planet that literally everyone knows that Darkside wants to conquer, gain too much attention (all the green lanterns are ready to stop the ship in any sign that they are going to attack) (the justice league is absolutely ready to stop the beginning of a total war between them and Darkside, with all backup plans possible in hand)

Imagine their faces when, Danny, Sam and Tucker just land on firm earth, dress human normal teenager clothes and just go like, and start to explore all the type of things in the first city they see

It could go anywhere from here, the first city could be Central City, and Bart would just go straight to them and immediately be their friend (he is from the future and knows these tree legends too damn well, he wouldn't waste the chance of becoming their first human friend)

Damian, who is used to have more and more older siblings , suddenly has a younger sibling who is not his by blood, but has a link to Lazarus pit

I can imagine him being a "omg, I'm a older brother now, what am I gonna do", and in the start be a little irritating with his closed face/ hard to read emotions, but slowly begining to be Danny's favorite older brother, and acting like an overprotective older brother

Or maybe he wouldn't treat Danny like a younger brother, but as an equal, a force to be recognized and they begin to be partners in crime (the batfam is very surprised because they thought Damian would be jealous of him, bc he was not the youngest anymore