Klaus had lost four brothers. One who left, and three who died. Two he was there to witness, and oh so helpless to stop it.
Kol was the recent one, and it was never meant to happen. He was supposed to fall to a dagger, unable to harm or be harmed. But Klaus was too late. He raged. He sobbed. And when he was free of that witch's prison, he hunted.
The first to fall was the Witch.
Her death was swift, and with it was the end of the Bennet line. A great loss to the witching world, but not for him.
The next to fall was the Doppelganger.
He took his time with it. Beating her, draining her, over and over until the wretched woman whom caused so much trouble was to broken to fight back. He staked her, and left her body for her sire to find.
The last to fall was the Hunter.
He knew the consequences, but they were worth it for his brother. For Kol.
He reveled in the kill, taunting and teasing until he grew bored and ripped his spine from his body with his bare hands.
When the curse took hold, Klaus was alone. Rebekah could not help him, and he would not suffer her the sight of him on the edge of insanity anymore. Kol, his little brother whom he once taught to hunt, who followed him around asking so many questions not unlike Henrik, who was there to witness every last moment of the first time the curse took hold, was gone. And Klaus was glad to take the curse in exchange for vengeance. He would suffer alone.