Appearance and Personality
Based off Crisis Core: FF7 - Copied from the Final Fantasy Wiki
Genesis's physical appearance is based on Gackt, who is one of the most famous Japanese Pop/Rock idols. Gackt also wrote and performed Dirge of Cerberus's theme song, "Redemption" and actually wears the Genesis costume in the music video, though his hairstyle has changed.Beyond this, Genesis's design bears similarities to Sephiroth, including the long coat, black clothing underneath, black boots, shoulder guards, and a large sword. Genesis is right-handed and bears a large wing on his left side, in contrast to Sephiroth, who is left-handed and has a wing on his right side. While Sephiroth's uniform and design are predominantly black and white, Genesis's is red and black. Gackt had a small amount of input on the costume design, mostly to ensure it would allow for easy movement, but also to help settle on the color scheme, which had previously been intended to be either white or black.
In the Game: Crisis Core's beginning portrays Genesis as a deserter, arrogant and childish. He even plays a trick on Zack after they meet in Banora. At first, he seems to be a simple character, but as the story progresses, the conflict within Genesis becomes increasingly visible.
Genesis was adopted, causing him to feel betrayed by both his true and false parents, one of the reasons for his departure from SOLDIER. His main source of turmoil comes from the secrets of his birth he discovers after the injury he sustains during training, that leads him to resent Shinra and all those associated with it. His seiyuu, Gackt, says that his narcissistic and destructive personality make Genesis an interesting character and makes him authentic.
Darkness and Light
In Darkness and Light, his destructive and narcissistic personality remain but more from revenge against the Realm of Light for attempting a Darkness experimented Project on them to create Darkness combating Supersoldiers, Genesis and his "friends" have revealed that they are a genetic mutation of Black Blood. Due to being a mutation, they don't have the Black Blood themselves however their attributes are greatly advanced compared to other Denizens of Darkness whom lack Black Blood, allowing Genesis to be very destructive indeed.
Genesis' History is similar to Sephiroth's, he was adopted from a young age and was revealed to have been the offspring of Project G which was one of two projects to create Darkness fighting Supersoldiers by mutating Black Blood with the Element of Light, this however proved to be too dangerous as all the Element of Light did was to mutate the Darkness and in the process made the being not only a Denizen of Darkness but also stronger than most organisms.
Meeting Blaid and Joining the Dark Empire
Genesis hid out with Angeal and Sephiroth at Villain's Vale prior to it being occupied by Dark Forces, Sephiroth led Blaid to their safe Haven after facing Blaid in a fight and learning of Blaid's connection as heir of the Dark Empire causing three powerful allies to aid the Traitor Keyblade Wielders, eventually they would follow after Blaid whom had formed the Dark Empire once again in the Realm In-Between.