Yes, Arno and Elise did end up together and conceived two children, one on October 7, 1799, and another on March 16, 1808. Their names are François Charles Dorian and Juliette Marie Dorian. François became a Master Assassin of the French Assassin's Brotherhood, while Juliette became a Master Assassin of the British Assassin's Brotherhood. Both of them are highly skilled assassins that became pioneers for their respective brotherhood branches.