Monster
I do not own Merlin
This is different than my regular style. I've noticed that as season four progresses Arthur is becoming well... he's undoing a lot of character development. I know he's in pain, but most of the pain is his own fault. Basically this is an exsplaination for him becoming such an angsty little prat that's been treating the people he's closest to like dirt.
Arthur was always afraid of the monster. The monster was strong but mean. It could never have any friends. The monster did things like attack camps of innocent druids. The monster killed when a warning would have done. The monster was cruel to servants and uncaring to anyone below it.
His father loved the monster. He loved when the monster showed no mercy to his enemies. He loved when the monster bit Arthur's tongue to keep the prince from disagreeing. His father loved the biddableness of the monster. The monster was his to command.
Arthur hated the monster, he felt it strangling him and sucking away his life. When women and children where killed he couldn't stop the monster. He couldn't argue with his father. He couldn't stop from jeering at the servants when he humiliated them. He couldn't stop loving his father…
Eventually Arthur gave up to the monster. He became Uther's perfect son. The monster was the perfect man in Uther's eyes. Arthur himself had no fight left.
Until the dark-haired peasant stood up to the monster. He wounded the monster enough for Arthur to fight it again.
The battles were long and hard; when ever Arthur was around Merlin he gained the upper hand but whenever he thought of his father the monster gained strength. However, now Arthur knew he could win, he was confident. Arthur would never be truly trapped by the monster again. He was able to speak against his father! Fall in love with a servant! Defy direct orders if he knew they were wrong!
When Morgana gave into her monster, Arthur couldn't see another explanation, Arthur's monster nearly died. How could the monster have a man like Uther as its master? But then the monster made its plea, the one Arthur had never been able to resist, "You love him Arthur Pendragon. He is your father. What kind of son would you be if you didn't make him proud? You may pretend otherwise as you treat your servant as your friend and love yet another but you are still his son. You are me. I am him." So Arthur saved his father.
The monster had no more strength with Uther being so broken. Arthur was ashamed at his joy. He believed the monster would never control him again.
Uther then died and the monster consumed him once more as it grieved but Arthur removed it in the morning. He would never have to deal with the monster again so secretly, in the deepest recesses of his mind, he celebrated.
Agravaine awakened the monster. Telling him he had to kill a man in cold blood. Reminding him of what his father would have done. Arthur realized he would never be rid of the monster and in his depression he surrendered half of his consciousness. He killed the man and started a war. He broke up with Guinevere. He let his uncle question Gaius as a traitor. He banished his fiancee and agreed to have one of his finest knights die painfully. He treated Merlin like a servant. He snapped at him. He was cruel. He threatened him with exile twice. After all, the monster didn't have friends- especially not servants, especially not servants who fought monsters.
Arthur did rise over the monster- when it became to painful to not do anything. He apologized, he fixed things. That still wasn't enough. The monster was winning.