Okay, let's get creative. Is this a Misdreavus?


Behind my gate,
I lie in wait;
Misdreavus' red sphere are reminiscent of the Philosopher's Stone from Full Metal Alchemist, which prominently featured the "gate" between two worlds.

I stay up late
So I may sate
My hunger. Fate
According to the RS Pokedexes, Misdreavus uses its red spheres to absorb the fearful feelings of others and gain energy. (This is also another reminder of Full Metal Alchemist, as the Philosopher's Stone is made by absorbing human souls.)

I would equate
To those I ate
Behind my gate!
Misdreavus resembles the beings beyond the "gate," who devoured Edward's limbs and Alphonse as payment for the Grand Arcanum (sp?). It also uses Pain Split to drain the strength of others.