As per Divyavadana, he was a follower of the Tirthikas and used to criticize the Buddhist monks for living a comfortable life. He was made to sit on the throne by the courtiers. When Ashoka found out about that, he convinced Vitashoka to become a Buddhist. He became a monk and practiced self-discipline rigorously.
Names of Vitashoka
Vitashoka is referred to as Tissa (or Tisya) in Sri Lankan texts. Theragatha commentary observes Tissa and Vitashoka as different individuals. Other sources call him Vigatāshoka, Sudatta, or Sugatra. The Mahavamsa later names him Ekavihārika.
Biological Brother of Ashoka
According to the documents available, Vitashoka’s mother was Subhadrangi also known as Dharma in popular culture. So, while, Sushim and others were stepbrothers to Ashoka, Vitashoka was his real brother.
In the Divyavadana
According to Divyavadana, the death of Vit Ashoka was an accident. The story goes that someone in Pundravardhana (place in North Bengal now in Bangladesh) drew a picture of Gautam Buddha bowing before Nirgrantha Nataputta (monk following Jainism). The picture spread in Pataliputra too. The news was heard by Ashoka.
Next, he decided to punish all the Nirgantha by rewarding people to kill them. Unfortunately, someone killed Vitashoka assuming him to be a Nirgrantha. The head was taken to Samrat Ashoka. When the Chakravartin identified the head of his brother, the remorseful brother ended the custom of giving orders for execution.
However, according to the more authentic works based on Ashoka’s life, Vitashoka’s fate remains unknown after Ashoka becomes king. Some scholars suggested that Vitashoka may have been a general or a minister of Ashoka.