The Insiders originally ran as a cross-over between Teen Titans and The Outsiders.
Part 1: Superboy has been convinced by Robin to share the truth of his genetic heritage with the rest of the Titans; only he and Robin know that 50% of his genetic make-up comes from Lex Luthor. As Superboy prepares to speak to the team, a hypersonic signal attracts his attention to a laptop where an audio connection has been made and a voice utters the phrase “Aut vincere aut mori.” – Either conquer or die. The trigger phrase makes Superboy shave his hair off and carve an L into his T-shirt before facing his team-mates and attacking them. The Outsiders, meanwhile, believe their team member Shift to be a traitor, only to have Indigo – the robot from the future that was instrumental in causing the death of Donna Troy in Graduation Day – reveal herself to be Brainiac 8.
Part 2: Attacked by their team-mate, the Outsiders rally as best they can and fight back, Shift struggling with the emotional impact of attacking his girlfriend. Eventually they manage to force her to flee before they re-group at STAR Labs where they meet the Teen Titans. While the teams struggle with who to blame for their own battles, they are surrounded by dozens of Superman robots. Beneath the abandoned Lexcorp tower, Lex Luthor – wearing the armoured battlesuit he donned at the end of Public Enemies – with the still controlled Superboy at his side, is joined by Brainiac 8 and her grand-father, Brainiac.
Part 3: Luthor and Superboy talk with Luthor explaining why he helped create Superboy; in order to hurt Superman, Luthor made something that he would love before taking control of it and using it to destroy Superman. The Titans and Outsiders battle against the Superman robots that have been activated remotely by Brainiac 8. She and Brainiac talk with Brainiac 8 at a loss to understand why Brainiac has not yet abandoned his biological form. With the Superman robot threat ended, the Titans and Outsiders come to the conclusion that they are facing a coordinated attack but before they can do anything, Luthor and Superboy appear and attack them. Wrapped in Wonder Girl’s magical lariat, Superboy is blasted with magical energy and freed from Luthor’s control until he speaks the trigger phrase once more. Brianiac 8 appears with Brainiac in tow and captures Wonder Girl, confronting Shift and telling him that the only way to save Wonder Girl is for him to kill Brainiac 8.
Part 4: The teams attack the villains and are stopped time and again until Wonder Girl attacks Superboy, trying to return hi self-control. Seeing this, Luthor attempts to kill her to prevent her confusing Superboy. Confronted with the site of Wonder Girl in such pain, Superboy overcomes his programming and stops Luthor though he escapes. Nightwing convinces Starfire that she can defeat Brainiac if she stops holding back; she cripples Brainiac’s ship with a huge burst of energy. Shift attacks Braniac 8 and causes her Indigo personality to come to the fore briefly; Indigo demands that he kill her in order to prevent her Brainiac 8 side from resurfacing and attacking them. With great regret, he does so. The teams survey the damage and Nightwing quits the Outsiders. An epilogue reveals Donna Troy watching the teams.