You had been just as enraged as your father when Rick and his little group came through and massacred some of your people. So, when the lineup came around, this was the first one you felt was truly deserved.
Except you got two good things out of it; revenge and him.
Rick's son, Carl. The entire time, you just found yourself oddly drawn to him. Maybe, it was the cold look on his face, or the fact he only had one eye; but it didn't matter, you were interested.
Then, the little shit started causing nothing but problems from then on. He tried to kill your men, threatened your father constantly, and it was annoying.
This time, when you guys got back to the Sanctuary, your dad seemed especially agitated with Rick. Why? You didn't really know...or care. Until, he instructed you to bring Carl here, something about tricking Rick or some other bullshit.
You weren't sure if he meant by manipulation or force, so you guessed the latter. Surprisingly, it was easy to get him back there after a blunt hit. You even left Rick a forged note, posing as his son.
When you got back, you felt a little bad about putting him in those dingy cells. He technically wasn't here because he did something bad, so you tied him to a chair in your room as if you were in some crime movie.
When he came to, his face went from confused to agitated when he saw you, trying to get up to attack you only to find out he couldn't. "Untie me, now!" He demanded.