A/N: New chapter a day later. WOOOOOO!
"Alright, remember the plan. Let's do this. Dubs, do the honors." Robin said, albeit hesitantly.
Dubs nodded, "Temporary Assimilation of room occupants to blend into Brainiac's bioorganic matter using Motherbox tech initiated, prepare for a slight loss of consciousness and minor discomfort." He droned out as he manipulated the matrices of his own Motherbox-like technology to link everyone into his own tech temporarily with tech that made them appear to look like Brainiac-influenced people.
Once the assimilation was done, Dubs moved everyone around a bit, "Testing neural link. Don't panic, I will only exercise this ability in situations of absolute necessity." He said as everyone was forcibly moving their joints on his commands to their neural networks.
While no one actually panicked, there was a mutually uncomfortable vibe knowing he could influence any motions they made. Robin was the one who voiced concern for everyone.
"This is temporary, right?" he asked when Dubs stopped checking for errors.
Dubs nodded, "I don't like this any more than you guys. I will remove this when it is no longer needed, I swear. Ian, initiate the portal."
In moments, they stood on the Injustice Earth in a small cave near the edge of Central City. "So if our location matches, we emerged right where Captain Cold brought her but that would mean—"
"NOOOOOOOOO!"
Robin shot off like a bullet toward Star's screaming, knowing they had little time to stand and chat when his girlfriend was screaming like that.
"Well, now we know where to go…" Kirsty sprinted after him, followed closely by everyone else.
"Were we always this fast?" Terra asked as they ran.
"Artificial muscle enhancement on my part." Dubs offered slightly embarrassed that he had used his current neural-linked tech to help them out and someone had taken note of it.
Ian nodded, "that's helpful."
As soon as they all found the building the screams were coming from, Robin broke down the door, furious.
Captain Cold stood there with a few other Superman-Brainiac-influenced goons standing around the device attempting to restrain Starfire. She appeared to be in pain, caused by the machine clamped around her limbs, seeming to be coursing with electricity.
"Cold using electricity? That's new. No Robin wai—" Ian spoke as Robin ran out to engage the enemy, followed by Malgand'r rushing out and slugging cold in the face.
"Azarath Metrion Zynthos!" Raven shouted, breaking the machine holding Star captive while the others helped take down the rest of the men. Floyd shot and ran, suddenly disappearing midway through the fight.
Once Starfire was free she nodded, "Thank you, friends! Wait… where is Beast Boy?"
Terra comforted Beast Girl as she began tearing up while the others explained the other missing person.
"Superman knows we're here now. Looks like Deadshot actually went off to alert him." Dubs said. "He'll most likely have a lot of his lackeys come to mop the floor with—"
"Guess again." A chilling voice called out as Superman himself descended into the room. "I didn't kill all of you the first time because you ran. If you're done running, I suppose it's time I finish what I started."
Several cables shot towards the group to assimilate them to Brainiac's consciousness, but on contact, Dubs used his own programming to cancel the effect out on the neural level.
"What? Ah, I see. Cyborg's bastard." Superman used his speed to come at dubs with intent to maim.
What he didn't expect was Kirsty to suddenly use a golden blade to cut off his arm.
Ian casually walked over to their foe, "Show us where Beast Boy is, or I won't be merciful." He warned.
Superman laughed, "You expect me to be so afraid of you Scott! A demon in a new costume isn't going to-ACK!"
Ian opened his demonic eye. "Oh, you misunderstand, Clark. I was talking to Brainiac. You, I have no intention of being merciful to. You've been subjugating Brainiac for your enjoyment and taking earth as your personal plaything. In order to release that many people and make the world go back to normal, that would mean rewriting history."
"So, you can't win. You admit it." Superman smirked.
"Oh? Actually, I'd say I just did! All I have to do now is wait for the rest of that yellow sunlight in your body to dissipate. So, here's what we're gonna do. Until Brainiac is freed and will speak with us, we will slowly crush your windpipe as you lose strength. After which we will call upon a certain father-in-law of mine and let him have this universe as a little gift for ending your reign. Believe it or not, this was personal the minute you tried to kill Catherine almost 4 years ago, but I have been biding my time. And as a gift to my former lover, who was in on this the whole time, by the way, she and her father are going to get dominion over you, Clark. You and all your little playthings will now live in hell for eternity, with a specific element coursing through your veins. Gold Kryptonite, bitch." Ian spat in Clark's face.
"G…g…gold!" Clark's eyes widened as he was now feeling the effects of the golden blade. "This is temporary you demonic—"
"Oh? I'm sorry, did you not know? Tenno, the one who sliced you with that blade is another person who has Motherbox tech in her, and she made that blade out of Gold Kryptonite Nanomachines, which are now fused to your blood cells. Checkmate."
As Clark lost his nerve staring into Ian's soulless stare of defiance and dominion, Brainiac finally took hold of his mind. "I applaud your ability to overpower my captor, as a reward, before I digitize this world, I will give you a look at Beast Boy."
In a second, a boom tube revealed BB standing there primed for a fight, guarding Brainiac.
"As you said, Scott, checkmate," Brainiac spoke with a small smirk despite his computer-like tendencies.
"Oh really? I just infected Clark, who happens to be your main body, with microbes that target any technology aside from the nanotech keeping him subjugated. You have maybe five minutes before you are inoperable." Ian smirked.
"You said you'd be merciful!" Brainiac spoke as he attempted to undo the infections with little success.
Ian yawned, "Did I? I don't remember that… or maybe since I am a demon, I was lying."
Dropping a frothing normal Clark who had been Brainiac's primary body, Ian looked around. "Dubs, release us from your control."
"That was… hard to watch." Terra shuddered.
"It was that easy?" Catherine looked at Clark's convulsing body.
"To be honest I was only able to get through it because of Scott's absolute hatred of Supes. I would have pissed myself otherwise." Ian sighed.
"And what about BB?" Cyborg asked.
Beast Boy shocked everyone by relaxing, "Poison is apparently a microbe." He shrugged with a grin.
"YOU WERE FAKING?" everyone shouted.
Ian sighed, "Alright, time to send these people to hell. This world isn't gonna be able to recover in any feasible way, as Dubs said, he ran the simulations. There are zero that end favorably for the people here. The reason he couldn't find what was an acceptable outcome was that he didn't run one where the universe was subjugated by Trigon."
Raven crossed her arms, "And how is that acceptable?"
Ian shrugged, "Because you from this universe would be in charge. Trigon doesn't bother with politics or rule, he conquers, he doesn't play with the lives of those who survive. AZARATH METRION ZINTHOS!"
A demon pentagram appeared and in it stood… Raven?
"Tell Trigon this planet and everyone on it are now his. A gift from your ex, to apologize." Scott completely changed his posture and tone in front of the older and evil version of Raven.
However, this Raven looked at the occupants in the room, "I assume your plan is to run away again with these insects?" she gestured to the group, however, she suddenly stopped when she saw a mirror copy of her younger self, along with a good Cyborg, an alive Dick Grayson, Beast boy without muscles and a young Starfire.
"So wait… did you use reincarnation and space-time magic on a bunch of corpses or—" She blinked her four red eyes.
Scott simply stood, looked her in the eyes, and allowed Ian control. As his eyes changed, she frowned, "What sorcery is this?" she asked.
"Nothing you'll ever see again. Enjoy your rule, Rae." Ian smiled.
She slugged him in the face.
He rolled backward in the air where the good, young Raven caught him and sighed, "Tell father he is free to do as he wishes, me. As for us, we have a different universe to go back to."
The evil Raven smirked, "Well I did know about the plan to usurp Superman. You guys have my demonic thanks, I suppose. As the only act of goodwill I have done in a long while, perhaps I will simply look the other way this once."
Ian activated the portal home as soon as she turned around and they all vanished as dark clouds began encompassing the earth of Injustice.
A/N: I know it seems too easy. I did my research. Gold Kryptonite makes any Kryptonian lose the ability to retain sunlight, which literally makes them a regular person in every sense of the word. With this being true in Superman's blood cells due to the nanotech attaching itself to them, he will never recover again. and even if there was a fact of Injustice not having Gold Kryptonite, Ian could have spent the hour in the last chapter acquiring it with Warp's device, which is only one of the ways it could have been achieved.
As for last chapter, the eggs in one basket were the golden nanotech in question, and how Ian knew of its existence.
The meeting between Ian, Raven and Catherine was the fact he was going to summon Injustice Raven and had to make sure they were not going to interfere with magic considering they were the only two in the group who had the ability to block demon summons canonically.