During the Peloponnesian War, the Spartan misthios Kassandra encountered Ros at several places in Elysium. Ros seemed to travel the world a lot and would appear at safe places like the House of the Bloodline, Iapetos' Ruins and Persephone's Lost Outpost. When Kassandra first entered Elysium she was immediately greeted by Ros.
Later, Persephone tossed an artifact into a well in her palace, signaling for Ros to fetch it. The artifact turned Ros into Cerberos, confronting Kassandra who had been tossed into the hole. Kassandra was able eliminate Ros and extracted the artifact from its collar.
- Ros has a unique model compared to other dogs in Assassin's Creed: Odyssey.
- A giant bronze statue of Ros could be found in Persephone's Akropolis on the southwestern side, just above the Prosperity Terrace.
- Ros is short for Cerberos.
- Assassin's Creed: Odyssey – The Fate of Atlantis