What does the seal on Meliodas's forehead mean? How did he get this seal? In episode 5, when the enemy tried to steal his sword, this seal appeared on his forehead.



What does it mean?
SPOILER UP AHEAD!!!!!


   It is the symbol of the demon clan. Meliodas is a demon. This advancement is explained in the Manga. Although it is hinted throughout the series, but it is never really explicitly shown that he really isn't human until after the Kingdom Infiltration arc has ended. The Ten Commandments, a group of the most fearsome demons are revived. They were sealed 3000 years ago, yet Meliodas knows them all by their names. King confronted him claiming he was a demon. Although he didn't answer, it is obvious from the situation. That also accounts for his never aging body.The Ten Commandments know him well too. And Meliodas actually calls them his brothers in chapter 135. So, yeah, he is a demon. Later on in the manga, his past and identity is explicitly revealed to be one of the Ten Commandments.