Gilthunder

Gilthunder is a Diamond-ranked Holy Knight of Liones, son of the former Great Holy Knight Zaratras, and later the husband of Princess Margaret. Alongside Griamore and Howzer, he was one of the Three Misfits, a trio of noble troublemakers known for their pranks in the capital before growing into knights.

As a child Gilthunder adored the Seven Deadly Sins and was personally trained in swordsmanship by Meliodas, but he turns cold and vengeful after the Sins are framed for his father's murder, hunting them down with genuine cruelty. That coldness is later revealed to be a mask: Margaret was being held hostage to force his obedience, and once she is freed, Gilthunder returns to the warmer, more honorable person he was before.

His arc is defined by that tension between duty and conscience, and by his devotion to Margaret, whom he vows to protect no matter the cost. After the Holy War the two marry and have a son together, Chion, and Gilthunder settles into a quieter life as one of Liones' most trusted knights.