As the mob of grounders and Skaikru under A.L.I.E's control rushed into the throne room, one thought kept replaying over and over in Marcus's mind. Clarke had to be stopped; she would destroy everything if someone didn't reach her.
Almost everyone guarding the unconscious blonde was distracted when he walked through the door, except for Abby. She was holding a gun but he was certain that he could use their connection to get passed her, she didn't want to lose him the way she had lost Jake; she had told him as much before he left Arkadia.
He was making his way through the crowd toward the throne when he felt someone grab his arm. He turned to see Bellamy's mop of black hair come into view as he was forcibly turned to face him. They exchanged blows and for a moment before Bellamy managed to knock him to the ground and the younger man made the mistake of turning his attention to one of the grounders.
He might have stayed down, at least for a moment, under normal circumstances but there was no pain in the City of Light. No pain, only the drive to keep going, to protect the peace he now felt.
Once he was back on his feet he had no problem overpowering the younger man, grabbing him by the throat and slamming him to the ground. He leaned in with one arm on Bellamy's throat before adding his other arm and putting his full weight into the action of suffocating the boy he had been mentoring only a couple of weeks earlier.
Bellamy struggled against him, gasping for air. "Kane-" He managed to choke out, his eyes bulging. With one hand he tried to pry Marcus's arms off of his throat, tried feebly to push him off with the other. He tried to say something else but the lack of air and the noise of so many people fighting in close quarters drowned out whatever he did manage to get out. Finally, his brown eyes shut and his arms went limp, falling to his sides, but the force propelling Marcus forward still wouldn't let him stop.
It was then that something changed, just as suddenly as the the peace and clarity had come when he took the key, it left. All the pain he had suffered came rushing back, and the pain he should have felt during his fight with Bellamy hit him all at once. His eyes widened as he realized what he was doing, he pulled back so quickly that it caused him to stumble backward slightly.
He scanned Bellamy's bloodied face for signs of life but he found none. His eyes remained closed, his body terrifyingly still. "Bellamy?" He whispered, almost bringing his hand to touch the side of the younger man's face but stopping himself at the last moment, afraid to touch him for fear that he would lose himself again.
"No, please no," Slightly louder this time, as he struggled to find a pulse with his shaking hands. He had mentored this boy, watched him grow, and come to think of him as the closest thing he had to a son. He couldn't have just murdered him, he couldn't accept that.
He looked behind him, his eyes landing on Abby who was hurrying to help Clarke, making a small incision in the back of her neck. He turned back to Bellamy, still desperately searching for any signs of life, anything to give him hope, but he found nothing.
His eyes began to burn, tears pooling and then sliding down his cheeks as he finally brought his hands up to Bellamy's face. Realization hit him that his last words to this boy he had come to see as a son were telling him that he was lost to him, questioning his motives for doing the right thing. He would have to live with that, knowing that had been their finally conversation before he choked the life out of him. He turned back to Abby and found her and Clarke both watching him now, eyes drifting between him and the lifeless form on the ground.
"Bellamy," Clarke called, trying to stand but too weak to support herself. Abby made her sit back down before rushing to his side, searching Bellamy herself for any signs of life.
Marcus sat back to give her space, bringing his shaking hands up to run them through his hair. He had closed his eyes, his mind still reeling from everything that had happened the last few moments, when he heard a sharp gasp for breath.
His eyes flashed open to find Bellamy conscious again, staring at the ceiling as he continued to gasp and cough. Marcus found himself launching forward to pull Bellamy into his arms, relief washing over him and at least for the moment distracting him from the pain.
"I'm so sorry," He whispered hoarsely, "I'm so, so sorry." He kept repeating the words, over and over again until Abby tapped him on the shoulder, reminding him to let the boy breath. He pulled back, studying Bellamy's face again before repeating the words one more time for good measure, "I'm so sorry, Bellamy."