Arno Victor Dorian is the protagonist of Assassin's Creed: Unity. He was born in 1768, from a French mother and father who was part of the Assassin Order. His upbringing was one of high status due to being in a noble family, which had books and tutors for him to learn from.
When Arno was a young boy his father was killed at the Palace of Versailles. His father left him a pocket-watch, something that would he cherish the rest of his life. After his father's death, Arno was adopted by a childhood friend's father, François de la Serre, a Templar Grand Master. Although Arno was now the adopted son of a Templar, he was not raised to be one, out of respect for Arno's fallen father. His childhood friend, and daughter of François was trained and schooled in the values and skills of a Templar. Her schooling separated her from Arno, but it didn't stop the two from becoming romantically involved.
In 1789, François de la Serre was killed at a Noble event. Arno arrived to the Grand Master's aide, but was too late to save him, and was suspected of killing his adoptive father. Charged with his murder, Arno was thrown into the Bastille. While in prison he meets an Assassin, who recognizes his fathers pocket-watch and deduces Arno is the son of the Charles Dorian. The two train in swordplay within the walls of the Bastille using fighting sticks. Eventually the Bastille is stormed by an angry mob, as a result of the beginning of the French Revolution, and Arno makes his escape by leaping off the roof.