The only of the Seven Deadly Sins to be a very famous character from Arthurian legend, but the anime/manga twists the character to be female. Merlin spent most of her time grooming Arthur Pendragon to be the king of kings. But she helps the Seven Deadly Sins part time when demons come back as the Sin of Gluttony.
Probably the smartest of the group, she rarely ever was defeated. The only one of memory was being turned to stone by the curse of the Commandment of Truth by lying.
But she had some of craziest tricks with magic. Her greatest being her power of Infinity, which allows her to do certain magical things without fail for as long as she desires.
She is very protective of Arthur and fails to save him from the most powerful of the Demon race.
We discover her true form is that of a child, despite being one of the oldest characters in the series. I’m assuming her infinity magic was keeping her that same age.
During the original Holy War, she was given gifts by the Demon King and Supreme Diety to join either side and she disappears after refusing both. Making herself a legend of infamy to both the demon and goddess races.
I was surprised she was originally in love with Meliodas. But she let go of her feelings after discovering he was in love with Elizabeth. Very big of her to do so.
I knew Escanor and her weren’t going to be an item. But I was happy she returned some affection before the Sin of Pride’s death.
She actually plotted behind the scenes for the second Holy War to go just the way she planned. Bringing back Chaos and Arthur as its vessel. Which kind of makes her a traitor though her intentions weren’t exactly evil.