Go is a bioroid created to be a hero of humanity, with abilities far far beyond anything a human could possess. Despite their names as heroes and the fact most people admire them, Shioso knows the truth about them, that they are much more crooked and evil than people realize. Doing back room deals, murdering people and doing pretty much whatever they please with no consequences. 

He starts off as a typical seeming guy with a bit of an attitude, knowing that everyone loves and adores him. However once he's attacked by Shioso he begins to drastically change, showing his true personality. He becomes exhilarated at the feeling of an actual challenge but once the reason is revealed he totally loses his cool and begins to completely lose it. Becoming cold, cruel and selfish. Even admitting how he's manipulated the main female character after he killed her father without her realizing.

I picture him having a typical arrogant jerk type of voice, like someone who figures they're more important than everyone else, but the VA needs to be able to yell and show anger for this role.