It was revealed that Sean was the figurehed leader of the netmafia Gospel in Mega Man Battle Network 2.
When he was very young, both of Sean's parents died in a plane crash that was considered to be a Net Crime. Afterwards, he was sent to relatives that mistreated him, and with his parents fouratne, Sean could only find solace and trust in computers and the net as he grew to hate and mistrust the world. One day, he was approached by a stange NetNavi who tells him how he can make the world a better place.
After running away from home, Sean began to form Gospel, who members consist of people who also had their fair share of trouble in the world. Gospel has gone out of their way to perform acts of violence and terrorism, such as bombing a metro-way, nearly blowing up a dam, and even destroy entire country's network. Many of his goals were foiled by Lan Hikari and his NetNavi Megaman.exe.
Sean made Gospel's main goal to collect different type of BugsFrags in order to create the Ultimate NetNavi, Bass.exe; who he would use as a weapon to use on the world. Once he managed to get all the Frags, he attempted to fuse them together, which caused the city of Kotobuki Town to become eradited, and Gospel's base,an apartment bulding, to become flex between the real and cyberworld.
Seeing as this as the last stand, Lan and Megaman went to Kotobuki to take on the boss of the NetMafia. When the two boys meet, Sean was wearing a hologram disguise, trying to sway Lan onto his side, to make him see that the people of the world are all bad at hear, that they're all faking to be good. Sean then offered to have Lan join his forces; but being the main protagianist, Lan told the Mafia Leader to take his offer and shove it, Lan then sends in Megaman to deal with Bass.
While being inside the Gospel's Main Computer, Megaman is attacked by his friends, Gylde, Roll, Gutsman, and Protoman. Turns out that Sean had capture the Navis when Lan's friends tried to sneak in the building earlier. Unable to fight his friends, Megaman was on the verge of deletion, with Sean gloating about how trusting others had lead to Megaman's downfall, when his REAL friends showed up. It turns out that Sean just made copies of Mega's friends, who easily dispose of their doppelgangers, right before Bass is completed. Sean then talks about his plans to mass produce Bass and use his power to take over the world, something that even Chaud seems to fear but makes Lan and Mega more serious to fight, ready to face Bass to save the world.
Megaman fights Bass, and easily wins over the supposely "SuperNavi." After Bass's deletion, Sean's hologram stops working and everyone in the room for what he really is, a kid. Ourage at his deafeat, Sean begins to ramble on how Lan is making fun of him, to which the NetBattler denies. Sean then tries to another attmept of making Bass, increasing the radiation to dangerous levels. As everyone starting to feell the effect, Lan begs Sean to stop, but the boy refuse to listen. Lan tells his friends to get out so they can be safe, leaving him alone with Sean in hope make him stop; and when he ask Sean why is he doing this, the boy response by saying it hated it. Sean loads the power to 200% percent, as it creates a new, stronger Bass; then it soon began malfunction and morphs into a wolf like virus known as Gospel, which seem to ignore Sean's order and started to overload the computer systems to point where Sean and Lan pass out from the radition. But Lan was still able to operate Megaman with his heart, since the two had abond beyond that of any NetOp and NetNavi.
A 2nd Chance
After Lan and Mega defeated Gospel, they found Sean was still unconscious. Lan then discovered Sean's journal, which detailed his life, from his parents death, to his horrible realtive, and how lonely he was.
When Sean awoke, he was devastated, that he had nothing to live for anymore. Lan tries to calm him doing saying that everyone has a reason to live, to Sean rebutted that he hated the world, that everyone hates him and wanted to die. Lan then offered his hand and said.
"Once you've atoned for what you did...I promise, I'll be your first friend!"
To that, Sean merely paused... and cried.
Shortly after the downfall of Gospel, it was discovered that someone was controling Sean all the long. That all the attacks and the plans for making Bass was not his own.
I Battle Network 3, Sean returns to DenTech CIty after a world tour of doing good to see Prof. Hikari, who was recovering from an Attack from WWW, which Lan was unknowingly a part of. Feeling bad for what he has done, his encounter with Sean agian reminded him that he can't just mope on what he has done if he wants to set it right.
Sean also comforted Lan at the end of the game when Megaman sacrifice himself to save him from Alpha, reminding the NetOp that he was not alone, and that he is better now because Lan promised to be his friend.