Aiden was one of the Thundershade Family's servants; however, after he awakened a B-grade Life Seed a year back, Aeon's father William gave him some cultivation resources and asked him to leave the Family and follow the path of cultivation.
With a B-grade Life Seed, William believed Aiden should not be a Family's servant but focus on the Cultivation.
However, Aiden said that he could focus on both serving the young master and focus on the cultivation. It was the Thundershade Family that took him in when he was begging on the streets and provided him with food, clothes and shelter.
He said that he could finally repay the Thundershade Family because he could finally enter the Celestial World Tree and start cultivating.
William was helpless with Aiden's determination. So, in the end, he said that as long as Aiden could become a Life Blood Sergeant in a year, he would let him become Aeon's protector who would enter the Celestial World Tree in a year.