I wouldn’t say Shuyin had always been a bad seed. He just wanted to live peacefully with the woman he loved, but living in the years of the war completely ruined his plans.

Before the war he was a popular Blitzball player, I wouldn’t go to the length to say he was as cheerful as Tidus was, but he was probably happy with his life. He had fame, he was young, and then of course he had Lenne.

Shuyin was really stubborn and ready to do anything to protect the one he loved. He was also quite impulsive, he didn’t care too much about the risks and the consequences his action could have. He was probably aware of Vegnagun power, yet he didn’t think twice about using it. There was only a person who could reason with Shuyin, and that person was Lenne. In the end it was the respect and love he felt for her, that stopped him from using Vegnagun. He didn’t want her to die, but he also realized that she wouldn’t have wanted to take the life of many innocent people to save her own.

Deep down, Shuyin intentions were good, but failing at Lenne drove him mad. His negative destructive thoughts were so strong that prevented him from fading away. His emotions slowly prevailed over reason, they blinded him and lead him astray. Despair, anger and regret tormented him in the afterlife, pyreflies repeatedly made him remember his last painful moments. He found himself alone, being unsent for over one thousand years, with the guilt for his failure always burning.

Shuyin became nothing more than a shadow, wandering in the darkness, desperately looking for his lost love. However, after over one thousand year wandering on Spira amongst the living, he saw nothing had changed. People were still fighting over small things, just like at his times. His search for Lenne was almost cast aside by the desire to fix Spira and destroy it forever.