He was adopted by a couple who where commoners, after his family was slaughtered. He was only an infant when he was adopted, so he has no recollection of his true parents or family at all. The adoptive family cared and loved him as if he was their own, since they could not have their own children. (The adoptive mother would have complications of miscarriage).
Growing up, he had helped his parents as much as he could. From doing farm work, to going into the city to sell goods, practicing his skill with a blade. He had his mind set on becoming a knight. One of his early rivals a a child, would also become his rival as a initiate. However, as years went by, Achiru and Nath became friends of sorts. Even if it's a love/hate friendship. They both progressed through the ranks, even if Nath flourished in picking up rank much quickly then Achiru.
His adoptive parents had finally been blessed with a child of their own, after years of trying. They named their son Vellien. Achiru and Vel may not blood brothers, but Achiru treated Vel as if they where. When Vel grew older, Achiru would teach his younger brother a few things. From basic things like fishing, to weapon skills. During this time, Achiru had gained promotion to captain in ranking. Getting paid well enough, he would send money to his parents. Giving them a better place to stay in the city, and also allowing them to take better care of themselves.
Not long after, did the scourge invade the lands. Wanting to fight to save his people and family, Achiru put himself in the battle. Many had lost their lives in the battle with the scourge. The day the scourge broke into the city's defense, his parents where cornered by a few scourge. Achiru was there, and saw it, instinctively ran to help them. Defending them, until a death knight challenged him. The fight did not last very long, in the end, the death knight was the victor. Instead of killing Achiru instantly, the death knight broke the paladin's legs to keep him from getting up. Slaughtering Achiru's parents in front of him, before going back and finishing the job with the paladin. Impaling him with the large rune blade, through the chest.
He was raised as a death knight, who would serve the Lich King for a time. Even he did not know the length of his time of servitude. When the Ebon Blade rose for freedom, he was snapped out of the LK's grasp as well. Serving for the Ebon Blade until the Lich King's defeat. After the war was over, he went off on his own. Spending years just wandering the world, doing mercenary work. Going to Silvermoon finally to give his respects to his dead family, he encountered his brother. Vellien did not perish during the invasion. He was very much alive, and full grown now. Vellien had changed however, for the worst. His younger brother is an assassin, having to raise himself through these years alone. Growing hatred for his own older brother.
In order to keep tensions away, as well as pain, the death knight tries not to be around his brother. Because of many factors, Achiru is a grumpy person. Tends to give people the cold shoulder, as well as act like a jerk. Currently, he still tends to pick up mercenary work.