Yoona

Behave. You're too much of a bad boy. You're too curious. I was cheated on at that time, all because of you. No fun, no manners. You, devil, devil, you, you. You changed one letter...

(It's hard for me to fulfill all English subtitles, but to interpret in brief isn't beyond my English ability yet...XD) (First part, there was a brawl between Taeyeon and Yoona, due to...