Stiles and Theo in “Unfinished Business”

Stiles

I'm gonna find her.

Theo

You know you won't, Stiles. You're going to have to trust me.

Stiles

[exasperated] Trust you? The guy who murdered his own sister when he was nine?

Theo

[offended] Yeah, I was nine years old. I also believed a guy in a red suit came down the chimney to deliver presents. So, when three people in leather masks showed up and said that my sister wanted me to have her heart, I believed them, too.

Stiles

So, then, together you gutted and killed her? That's a beautiful story.

Theo

I watched her fall into the water and freeze to death in minutes. Do you think I had any idea what was going on?

Stiles

I think you pushed her. And I think you liked it.