Escanor the Lion's Sin of Pride was originally a prince from a kingdom named Castellio. When he was a child his brother named Daymond used to pick on him, until one day his power awakened causing him to accidentally break his brother's arm. His parent's then disowned him and the kingdom's forces mobilized to kill him. He was saved by a kind woman named Rosa who look a lot like Merlin. After he was saved he eventually met Merlin and Meliodas, thought wherever he went people feared him even when he saved them.

Escanor's personality and appearance changes between day and night. His power level cannot be measured. Out of all the Sins, he is the youngest. During the day he appears as a tall and muscular man and during the night his appearance changes into a small and skinny person. With the setting of the Sun, Escanor returns to his original, skittish self. During the Night his power level is at 15 and during the day his power level is up to about 114,000. At high noon his power reaches its peak, and he becomes "The One," described as an "invincible incarnation of power" by Merlin, for a minute. In this form, he surpasses Meliodas's Assault Mode, indicated to have a power level of 142,000. Wielding the limits of "The One's" power strains Escanor's body, incapacitating him for some time to the point of nearly dying. Ultimately, Escanor damaged himself more than the target of his full power.

When he first met Merlin he loved her at first sight. The reason why Escanor loved Merlin was because Merlin didn't fear Escanor like the other's did. He was jealous of Arthur because he had a great connection and relationship with Merlin, but when Artur stabbed himself, Escanor later found out that Arthur's relationship with Arthur was only a master/pupil relationship.