AN: I just watched Saturday's episode. I kind of feel bad for Knock Out at the end of it. His paintjob – which he probably spent hours buffing to perfection – is ruined. And no Decepticon will give a crap.

Autobot Base:

He never expected it to be this… exhilarating.

He could feel it swamping him, taking over slowly. A snarl built up, drowning out the noise form inside the base.

He couldn't see, and felt himself jerking as the poison leeched into his circuits and vital systems. The experience was agonizing, but he relished in it all the same. It was absolutely the strangest thing he had ever known.

Then the pain stopped altogether.

A rush of pure energy drove him to reactivate himself, to fulfill the single thing that occupied his thoughts – Megatron's orders were simple: Kill them all.

Outside of an Abandoned Mine:

Something wasn't right. The Decepticons were being far too defensive, carefully avoiding anything that could end the battle.

All of a sudden, Dreadwing called retreat. The Autobots hadn't even touched him!

Starscream, naturally, was furious. Arcee could hear them yelling at each other as they sped off with the Vehicons.

Ratchet was about to call for a GroundBridge when he got a call from June.

"Ratchet, dark energon is extremely dangerous to all transformers, right?" She sounded flustered, and a touch frightened.

"Yes." Ratchet wondered why she would ask that now. "Something's wrong, isn't it?"

"Knock Ou-" Then an animalistic sound cut her off. "Jack! I thought I told you to get Raf and Miko out of here! Ratchet, I'm opening the Groundbridge. Get here quickly."

Ratchet was about to reply when the transmission ended. He turned around, calling to his comrades. "Optimus, I believe we may have a situation on our hands."

The Prime nodded, signaling for the other three to return with them.

Autobot Base:

When they arrived, the place was a mess. Ratchet's tools and experiments were scattered across the floor; the communications' screen was overturned; things were trashed and pummeled to bits. It looked like a warzone.

And Knock Out was standing in the middle of it, his weapons drawn and ready for a fight. His head was low, his armor raised in palpable fury.

But that was not what made the Autobots freeze; it was the unnatural purple color of his optics.

"Dark energon," Ratchet breathed. He saw the ragged wound in the younger mech's hand, and the glowing shard of crystal protruding from it.

Optimus drew in a gasp of shock.

Bumblebee, Bulkhead, and Arcee took up positions on each side of Knock Out, careful not to scare him.

The red medic stared unseeingly at Ratchet, his circular saw buzzing as it activated. He lunged for his former mentor, a screech escaping him.

Optimus blocked the blow. "What have you done?" He hissed, bringing a clenched hand up to strike Knock Out in the chest. "How could you make this choice?"

Knock Out snarled at him in Cybertronian. "You know why. None of you ever trusted me." He aimed the remark at Ratchet. "None of you!"

Ratchet knew the Autobots were holding back in part due to his own reluctance to strike the medic he'd trained.

"We're stuck on this Primus-forsaken rock, and none of you ever listen! Megatron was going to kill your from the start! Ratchet, I told you over and over what his plans were, and you never stopped to think that I was right! Get over your pride and use the intellect you're supposed to have! You said you never used my intelligence because you were afraid to compromise my position, but it was always because you thought that you knew better and I was stupid. News Flash: I'm not and you better start learning that! Swallow your pride and get over it. All of you! You're as good as dead now. Stop fighting and accept the fate that was always going to be. Do you hear me? I'm going to kill you, and you can't stop me! Because you all deserve it! Every last Autobot deserves that fate that waits for them. Accept it! This was always your fate!" He threw Optimus to the ground, lunging with his drill extended in front of him.

Ratchet took the blow to his arm, raising it to cover his face. This wasn't Knock Out. This wasn't the quiet but capable apprentice he'd trained to be a formidable fighter and skillful medic. The poisonous dark energon had taken a firm hold on him, feeding off his confusion and turning it into hate and rage. Ratchet countered as best he could, but could not bring himself to use his weaponry. He knocked the red medic down, holding him while Optimus got to his feet.

Arcee and Bumblebee held Knock Out's arms behind him, struggling against his newfound strength. Bulkhead held his mace above his head, ready to bring it down should the medic escape.

"Megatron cares not for the lives of his troops," Optimus growled, fighting to keep his voice even. "And he would gladly let you die if he thought it would benefit him."

"I know."

"This is probably why he sent you here."

"I know." Steel edged Knock Out's reply. "But it's worth it if I can take just one of you down before I go." He stiffened as he felt the grip on his hands tighten. He snarled a curse that was quickly muffled by Bulkhead's hammer colliding with his head.

"Mind your manners," the former Wrecker said mockingly.

Knock Out's optics blazed with cold fury. He wrestled himself free of Arcee and Bumblebee, drawing his prod from seemingly nowhere. Calculating, quick, and deadly, Knock Out had Bulkhead pinned against the wall of the missile silo in less than a second. "Looks like I'm not the only one." His hiss was barely audible.

Ratchet now knew he had to act. He shifted his hands into swords, ready to attack.

Knock Out heard the sound of the transformation. He ducked Ratchet's first blow, but took the four successive directly to his chassis. He did not stop to worry about his ruined paint job, already devising a counterattack.

Ratchet stabbed Knock Out in the wrist, causing the latter to drop his weapon.

"Seems your T-cog wasn't wasted like you said it was." There was a touch of his old humor back in his voice, and he seemed to weaken. Already his optics were less purple than before, his attacks less smooth.

Ratchet turned to the others, dodging a swipe from Knock Out's drill. "Wear him down! The dark energon is burning out. If we can make him use all of it, he can be defeated."

Arcee jumped into the fray, landing blow after blow on the red medic, encountering little resistance. Bumblebee joined her, blasting Knock Out in the back. Bulkhead recovered from the shock of a mech much smaller than him being able to pin him so easily, soon joining the other two.

Together, the three of them drove Knock Out to his knees, but they did not stop then. They needed the medic to fight back for Ratchet's plan to work, but he wouldn't.

Knock Out supported himself with shaking arms, bracing against the floor to take the barrage of energon bolts dead on. Then his joints gave out, and he felt the strength he had earlier leave him completely. He was sprawled on the floor, waiting for the Autobots to finish it.

Optimus shouted at them to yield; their adversary wasn't moving. He looked at Ratchet. An unspoken question flashed between them.

Ratchet sadly shook his head.

"Lock him in the training room. He cannot hurt himself there."