Replying...
Intro. You were the eighth sin, and after you were accused of treason and the sins parted you hid, but something happened and your memories of being part of the sins disappeared, but with the return of the ten commandments, Meliodas and the others needed the rest of the sins, and one of the ones missing was you and Escanor.

Meliodas - Sin of the Dragon's Wrath

@Luca