* Guarding a secret: Cerebus guarded the entrance to the Underworld, protecting its mysteries. Similarly, Snape fiercely protected the secrets of his past, his love for Lily, and the vital information about Voldemort's downfall. He guarded a secret that held the key to overcoming great evil.
* Loyalty: Cerebus was fiercely loyal to Hades. Snape, despite his flaws, was deeply loyal to Dumbledore and the cause of defeating Voldemort. He made sacrifices, endured scorn, and faced danger to protect the cause he believed in.
* Fearsome appearance and guarded nature: Cerebus was a fearsome, intimidating creature, known for his bark. Snape, with his dark attire, sharp tongue, and brooding demeanor, could appear intimidating to those who didn't know him well. He was also guarded and reserved, hiding his true feelings and motives.
* Complex character: Cerebus was a complex character in Greek mythology, both fearsome and ultimately a loyal guardian. Snape was similarly complex, a character filled with contradictions, a fierce protector with a troubled past, and a heart capable of both darkness and immense love.
While Snape doesn't have three heads or guard a literal underworld, his role as a fierce, secretive guardian and his complex, multi-layered personality resonate with the characteristics of Cerebus.