theres Major symbolism between Cerberus and Vincent >.>. play the game and pay attention...its not physical in any way, I would tell you why but that would be a major spoiler.

(even if I put up spoiler's, people will look anyway)

just remember what cerberus's job is (in hell) and Vincent/chaos's "destiny"


but on another note; I do believe there is not actually a sad song or poem of cerberus, its just symbolism and for the title :/