Adi was the son of Andhak. He did a hard austerity of Brahma dev and got the boon of getting appearance of anybody by touching them. He also got boon of getting trained in fighting from Mahadev Himself.
Mahadev saw revenge in his acts when He was teaching him. Although Adi always denied for such claims. He wanted to enter into the family of Shiva. He was the son of Andhak who got birth from the sweat of both Shiva and Parvati. So he wanted to be the part of family of Shiva.
He learned different fighting styles from Kartikeya, Ganesha and Nandi. There was a wonderful opportunity for him to become a legend but evil mind and revenge can blind anybody. He had no interest in learning, but just revenge for the insult of his father.
One day when Mahadev wasn’t in Kailash, Adi started misusing his boon of taking appearance. He created misconception among Gana-Pret and Nandi. They all started fighting with each others.
When Parvati came to know about the evil acts of Adi, she threatened him but like his father Andhak, he was completely corrupt and evil. He didn’t listen and continued troubling everybody.
Adi wanted to throw everybody out of Kailash. He wanted to live with his father Andhak and with Parvati.
Everybody on Kailash got confused how to deal with the situation.
When Shiva got the information about the misdeeds of Adi, He furiously killed him with his trident.
When Andhak knew about the death of his son, he started looking for an opportunity to take revenge from Mahadev.
Sources & References
The Purans Volume – 02 by Chandra Shekhar