"Bloody Harry" was the leader of Brandon's original crew in Desolation Alley and was also his best friend. After five years with Millennion, he and Brandon climbed to the top of the organization's hierarchy, joining Big Daddy's "Family" and adopting the "Code of Iron," a philosophy of trust and loyalty to the organization. However, MacDowel took the Code lightly and made deals behind the organization's back, pulling strings and putting himself at the very top of Millennion.
When Brandon discovered this and confronted Harry, he was murdered, but Harry had no idea of the future consequences of his betrayal. Although Harry lacks the physical strength and agility of Brandon, he is charismatic and extremely cunning. In the anime, it is portrayed how the guilt of murdering his best friend drives him close to madness.
In the video game he is not fought directly, instead he summons Big Daddy, who had been transformed into a grotesque monster to eliminate Grave. When Big Daddy's twisted form is destroyed, Harry realizes he has nothing left to protect himself. Harry calmly accepts his defeat and allows Grave to kill him.(Source: Wikipedia)