Here is a idea about Kaldur and Black Manta

What if Black manta made a plan to kidnap Aqualad aka his son, and find a stone that can turn a person into a child, he was going to re-raise him. Black Manta also have someone to make him forget everything, will his team and Aquaman find him and turn him back to normal ?

Another idea

What if Black Manta has someone kidnapped Kaldur for him, Black Manta's have the Light to brainwash Kaldur into thinking he has always been with his father. Will his team and mentor save him.

Here a idea for Roy aka Arsenal

What if a villain kidnaps Roy and uses him for something related for Robin hood ( It can be your ideas and choices of what kind you want ) will the Justice League and Young find him and bring him back home.

Here is an idea about one of the Robins

What if when Jason was brought back by Ra's al Ghul, when he place Jason body in the Lazarus Pit. When Jason was brought back to life he was quickly knocked out or put to sleep before anything could happen, Because it can make some people go crazy or Insane. What if Talia or Ra's al Ghul told the young Justice and Batman about Jason, after letting Batman and the other Robins go see Jason who was still asleep or tied up to keep him from hurting himself, also Taila show them Damian her and Batman Child which shock all three of them. ( I will let you choose the rest )