Assassin’s Creed Revelations connects the earlier Assassin protagonists Ezio Auditore and Altaïr Ibn-La’Ahad. Ezio is the playable hero in the fifteenth-century storyline, while Altaïr’s life is explored through memories unlocked in Masyaf.
Ezio travels to Constantinople in search of keys that open Altaïr’s library in Masyaf. The keys contain recorded scenes from Altaïr’s later years, allowing the game to shift between Ezio’s Ottoman-era adventure and important moments in Altaïr’s history.
The connection is part of the series’ recurring idea that the Animus can reveal memories from different ancestors. Ezio eventually discovers Altaïr’s final resting place and recognizes the continuity of the Assassin legacy across generations.
Revelations was released in 2011 and concludes Ezio’s main trilogy. It is not a direct team-up in the same historical moment: Ezio and Altaïr live centuries apart. Desmond Miles also remains part of the modern-day framework, but the question’s historical pairing is Ezio and Altaïr.