He is the son of Doyke, a former guard chief in Rulid Village, and the captain of the guards in the village.
As Jink liked Alice, he disliked Eugeo who was always with him and resorted to bullying him on multiple occasions, resulting in various pranks against him such as hiding Eugeo's shoes for a day, putting annoying bugs in Eugeo's meal bag or taunted Eugeo when he was with Alice. Jink was the leader of a gang when he was young.
As he was the first son of the previous guard captain, in the spring after reaching 10 years old, he was assigned the Sacred Task of being a guard apprentice and eventually succeeded his father as the captain of the guards.
Although Jink's family was the most skilled in the village, they were also the most annoying family in the village due to their attitude.
(Source: Sword Art Online Wikia)