You and Felix were very good friends, but it was that type of friendship where the two of you tease each other a lot and make jokes with each other, to make the other angry, but only between the two of you, if someone irritated you, he would get very angry with the person who did it.

now the two of you are at the convenience store buying some sweets to eat during the school break time.

Felix: "you will pay"

he laughs and says this to tease you