Set during Season 5, episode 11. Mordred's feelings as he leaves.
Mordred felt the numbness seep through his veins, clouding his thoughts. His cheeks were wet from salty tears. His throat was raw, as if it were bleeding from all the silent screaming. Kara... Kara... Kara. Her name circled around his mind, deleting every other thought. It poisoned everything in his mind. It was all dark and scary. He was terrified for her. Terrified for her life, or more specifically, her death.
Fear. Desperation. Love. Confusion. Anger. Gushing floods of anger, white hot, driving him. Everything went red, and his screams echoed with in the dungeons. Or they would have if he had screamed. Instead, his screams were within his mind. Mordred felt like a caged animal, and in that moment he was. He felt the rivers of tears fall down his pale cheeks. It was getting hard to breathe through the emotions and anger and the sobs and the tears. He was shaking, his emotions aching to be let loose, his magic needing to come loose. It was driving him insane, atop of everything else that had gone wrong. His and Kara's death sentence, Arthur's cruelness, everything that could've gone wrong had gone wrong. At least they didn't know he had magic. Not yet, anyways.
He saw through his clouded eyes shelves shaking violently and the likes. His magic was reacting. Everything was needing to get loose... He need to be free... He had to save her... He had to get out. Sobs wracked his body, his arms around his knees. Everything was going to fast, far too fast. Was it just yesterday he had met Merlin the first time? When he first used his magic? Mordred didn't know, everything was going to fast. Everything was out of his control. He started shaking more violently, and barely contained the earth-shattering scream. His emotions were too strong, and his mind too weak to withstand them. And that's when he felt it.
He felt the noose around her neck tightening until it killed her. He felt everyone last one of her emotions, Kara's anger, resentment, hatred, and love for him. He felt her die. Her last thoughts, her last breath, her last heart beat. His head felt like it was ringing and it hurt, everything hurt. They became one. He was choking as she choked, but he didn't die with her. Although he wished he had. All his emotions had to come out. He started to shake. His emotions flooded his system, and they took control. There was nothing he could do.
Mordred let a bone shattering scream out, releasing it all. His magic was unleashed, destroying everything in its path. His cell door crashed to the floor with dangerous sparks flying around it. His breathing grew harder. Mordred somehow stood shakily, legs unreliable and vision blurred. He had enough sense to teleport away before knights came to check out the noise, but barely. His mind was reeling. Everything seemed darker. Wrong. Different. Evil. Mordred swore to himself that he would avenge Kara's death. He would get revenge on her death. On her cold-blooded murder.
Once he was safe in the forest, Mordred collapsed under a tree and just sobbed. He let everything loose, his anger, her hatred, their love. After a couple minutes, he pulled himself together. He had to be strong, he had to get revenge. On Arthur. On Camelot. On every single person who helped lead to her death. Merlin flickered across his mind like a candle in a windstorm. He would decide Merlin's fate at a later date. He had betrayed him, yet saved them in one.
Everything felt painful. Every breath, thought, heart beat, even blinking ached. He could almost see her, Kara's strong, calm, beautiful dead face still in it's noose. He knew that she was still hanging there, still swaying. It was sick, and made him want to throw up. How dare they treat her like that. They weren't showing the slightest amount of respect, because to them, Kara was just a girl who had tried to kill their king.
To him, she was the girl who had captured his heart and didn't let it go, even in death. She was the girl he had fallen for when he was younger, only to be reunited and then ripped apart. Forever. Mordred knew that she wasn't bad, just was affected by what had happened to her family. And they had still killed her. It was unjust, simply wrong. Arthur claimed he was a just king, but he killed anyone with magic. Killed anyone different, fought for what they believed in. And he would not stand for it.
He rose to his feet, blinked away his leftover tears, and started walking. Walking towards where he knew Morgana would be. He hated to admit it, but he had been wrong. She had been right. Her side was the side he would always belong on. They were fighting for the same affect. To bring down Camelot and rain Hell on Arthur Pendragon. He deserved nothing less. Mordred would do everything his power to hurt Arthur the way he had been hurt.
He wouldn't touch Guinevere, no, that would be sinking to the bastard's level. He would make his death as painful as possible. Arthur claimed murder was illegal, but he did it every time he killed a sorcerer, or a druid, or someone who was even suspected of having magic. The punishment for murder was death. So, by Arthur's own decree, he deserved to die.
It was twisted logic, but true. Mordred didn't care. It was logic nonetheless, and he would follow it. Arthur would die for his crimes. Evem if murder wasn't illegal, Mordred would have killed him anyway. Because what he did was just plain wrong. Inhuman. Evil. He would pay.
He walked towards where he suspected her camp was. Mordred knew Morgana would except him back with mostly open arms. They shared a connection, something he couldn't ignore. His hatred for Arthur had made everything crystal clear. He would kill Arthur Pendragon, and he served everything that was coming to him. And he wouldn't give any mercy. Not after killing his lover. Not after killing his chance at a happy ending. Killing his happiness. Arthur made his life break down in pieces and he would get him back for it. Mordred promised himself and Kara he would. And he refused to go back on his promises.
He would kill Arthur Pendragon if it was the last thing he ever did.