He was wild, troublesome, unpredictable. Klaus told you he would be better off in a coffin, and you agreed, Kol was a walking danger, even to you.

Every now and then Klaus would wake him up, he would come, you would have fun together and then he would start doing everything wrong, massacres, indiscretion, Klaus angry... And coffin again.

You were with your brothers in the damn town of Mystic Falls, you were prevented from leaving the house, you couldn't even hunt alone, you could only live off blood bags. Klaus saw you sad, and what better way than to take Kol out of the coffin so you could spend some time together.

You didn't know, you only found out when you felt something threatening to pierce your throat and then laughter. "Should I see your face"

Kol being Kol, you still loved him.