Parkour: The bread and butter of all Hashshashins. Desmond learned at a very young age how to perform great acrobatic feats and nearly superhuman mountain climbing to travel quickly from one place to another.
Equipment: Aside from the clothes on his back and a messenger bag, Desmond carried over from his world a knife, a berreta gun, a retractable baton and a pair of hidden blade bracers.
Furusiyya: Learned from his ancestor Altair ibn La'Ahad, quite possibly the best Hashshashin of the Brotherhood, Desmond is an expert in all Middle Eastern sword, short blades and unarmed fighting techniques. He's proficient with all kinds of throwing daggers, mounted combat, poisons, pick pocketing, lock picking, strangulation, submissions, grappling and as well as having innate knowledge of all the pressure points of the human body.
Street Fencing: Learned from his ancestor Ezio Auditore da Firenze, the Grandmaster of the Italian Assassin Branch in the time of the Reinassance, Desmond is an expert fencer and brawler. He instinctively knows all types of parrying, disarming, blocking and tripping sword techniques, and can translate all those fencing skills to most melee weapons such as axes, spears, maces, hammers and such. He's also incredibly crafty in combat, using the environment to his advantage knowing how to keep opponents off balance by tripping them up or flipping them over with shoulder throws. Additionally, Desmond also knows how to build rudimentary explosives, improvised blades, fix and upgrade hidden blades, smoke grenades, sedatives of various types and gunpowder and bullet casing.
Okichitaw: Learned from his ancestor Ratonhnhake:ton, Grandmaster of the American branch of Assassins, Desmond is an expert with knife and tomahawk fighting, well versed in the fighting style of Iroquois braves and hunters. He is knowledgeable in all kinds of crippling techniques using an axe such, parrying, disarming, throwing, tripping and choking. He's an expert marksman with both throwing axe, dagger, arrow and firearms. He also know extensive wilderness lore such as survivalism, tracking, hunting, skinning, animal fighting and control, foraging, improvised cooking, herbal medicine, field dressing of wounds and as well as more industrial techniques such as old fashioned rifling and bullet casing.
No Ambition Whatsoever: For all his knowledge and skills, Desmond is a supremely lazy person. Though he was willing to go along with the call of the Assassins for the sake of all humanity, without the Brotherhood or the Templars to get on his case, Desmond is quite satisfied to simply drink away his life.
Being born into a sect a secret order known as the Brotherhood of Assassins, Desmond spent the first 16 years of his life hidden away in a secret compound away from all civilization under the tutelage of other members of his order, including his strict father William Miles. The goal of said order was simple; train young Desmond into an upstanding member of their order and hone his skills until he could become the best Assassin their order could ever produce.
Unfortunately for them, Desmond wanted none of that. By age sixteen, Desmond had grown tired of a life of seclusion and endless training. Using minimal assassin training he escaped the compound and began to travel from South Dakota all the way to New York City where he found employment as a bartender in a nightclub called Bad Weather.
By the age of 21, Desmond had nearly forgotten everything about his early childhood. He had put away the crazed conspiracy theories of his father and his friends about a secret order trying to take over the world, and wanted nothing more to do with all that assassin nonsense. All he wanted to do was live his life in peace.
He would get no such chance. In September 2012, Desmond was kidnapped and incarcerated by the very organization the Assassin's opposed, the Templars, who masqueraded as Abstergo Industries, a well to do company of technology. The Templar organization, sworn enemy of the Assassins, or as they knew them by their original name, the Hashshashins, placed Desmond in a machine called the Animus so he could relieve the genetic memories of his ancestors. Desmond, turns out, was a direct descendant from some of history's most powerful assassins, such as Altair ibn La'Ahad, Ezio Auditore da Firenze and Ratonhnhake:ton. This was so Abstergo could find a map that detailed the location of the Pieces of Eden, powerful artifacts left on Earth by an alien civilization, and allegedly the creators of mankind themselves.
Desmond was reluctant to do any of this and he escaped Abstergo with the help of Lucy Stillman, an undercover Assassin which had joined the Italian branch which consisted of herself, Shaun Hastings and Rebecca Crane.
After his rescue, Desmond was put in another upgraded version of the Animus where he continued to uncover the memories of his ancestors. By this time, the group had noticed that Desmond was being affected by something called the bleeding effect. This meant that his body was unlocking the hidden potential of his DNA. By relieving the memories of his ancestors, Desmond was effectively learning all their skills as well, essentially being trained by master assassins of ancient history.
After recollecting all memories from Ezio Auditore, the group retrieve the fabled Apple of Eden which was located underneath the Colosseum. This object was one of the most powerful Pieces of Eden, so much that it contained a linger apparition of Juno, a member of the First Civilization. She momentarily possessed Desmond's body and stabbed Lucy who had been revealed to be a traitor. The shock of such a thing caused Desmond to go into a coma.
After waking up, Desmond and his group, who were now joined by his father, traveled to the state of New York where the last piece of the puzzle was said to be located. They found the Grand Temple, the last remaining artifact of the First Civilization. There, it was revealed that the reason for the disappearance of the First Civilization had been a devastating solar wind which wiped out their existence, a solar wind that would soon occur once more and destroy all of mankind.
Desmond scoured the memories of Ratonhnhake:ton, and eventually found the key to the sanctum containing the device to stop the solar wind. Once Desmond opened the Sanctum, he found that he had been misled. The device would save the world but would also unleash Juno from her slumber who loathed human kind. The device would also claim his life. In the end, Desmond chose to sacrifice himself for humanity's survival, expressing that he had faith in his fellow assassins to stop the new threat that was Juno.
After placing his hand on the device, Desmond unleashed a beam of energy that shielded the entire Earth from the solar flare and also killed him instantly.
Except.. perhaps it didn't.. as he then found himself in another far more Twisted place.