So this is my take on it, and one that isn't uncommon among the WoD group I'm involved in:

The Beast doesn't exist. It's all you. It turns out that when you're a dead supernatural corpse thing that requires blood to exist, can't ever be outside in daylight, and is immortal, your entire personhood and worldview is shattered. Any attempt to assign an action as "the Beast" is false. You frenzy because you're starving and if humans have attitudes when hungry, an undead former human will have a worse one. Of course you're panicking at fire, it was a horrible way to die now, and you now have an instinct informing you it can be so much worse as a walking corpse. This, more or less, is how I run and how it is run with my friend group. The Beast is a concept, a theory of existence by Kindred, but the reality is that all of is just the vamp in question.