Otacon, born Hal Emmerich, is a character from the Metal Gear series who makes his appearance on Metal Gear Solid. He is the one who helped designed Metal Gear REX, unaware of it's true purpose. With guilt all over his feelings, he assists Snake in dissembling Metal Gear REX. He returns in Metal Gear Solid 2: Sons of Liberty, as part of the Philanthropy group, an anti-Metal Gear organization. He returns in Metal Gear Solid 2: Sons of Liberty and guides Snake through the tanker, Discovery and the disguised oil-cleaup facility, the "Big Shell". During the Big Shell chapter, Otacon's half-sister, Emma Emmerich, holds the data chip to implant a computer virus to stop Arsenal Gear's computer AI, GW. She is stabbed on her way to the computer room and later dies. Otacon's father had committed suicide prior to Metal Gear Solid and Otacon's stepmother had a seductive relationship with him (which is the cause for Otacon's father's death). His nickname deprives from "Otakon"http://en.wikipedia.org/wiki/Otakon, as his main interests are anime and manga. Overall, the development of Otacon is from a cowardly weak man, to a man who stands for courage.
In Super Smash Bros. Brawl
Otacon appears in Shadow Moses Island and communicates Snake via Codec and informs about the fighters in the battlefield.