Normally "hmm" would be something that I would say when I can't decide where to start tearing an essay apart. But in this case, my "hmm" is due to the fact that this essay caught my attention. No- it caught my attention, and I enjoyed it. When I first read the title, I was thrown off by the topic in a negative way. However, your writing quickly destroyed my bias.
You use fantastic descriptions that seem intricate, but are actually short and precise. This creates an absolute imagery that is very vivid. At the same time, this imagery is somehow dark- devised by the tone and voice of a vampire slayer. I liked it.
Moving on to criticism. This essay is very well written- so you don't need help with the basics. I'm going to hit the nit-picky stuff and be specific, which is something I normally wouldn't do when editing someone's essay.
...at 4:00 am and envelops my mind: the vampire of self-truth.
In this case, your repetition of vampire is good. I was thinking it may be made even stronger though if you use a word like "monster", "demon" or "banshee". Self-truth lacks the proper punch to lead into the meat of your essay. It doesn't feel defined, and instead feels without purpose.
...was alone (yet again)...
I'm not sure this is necessary. It makes sense to emphasize it, but at the same time it does not feel important. It's up to you to keep/delete though.
She was, in essence, me, only better.
This sentence is not needed and is excessive.
--odd, because I hate bologna
Again, not needed. They don't need to know that you hate bologna, and it doesn't add much to voice.
...my life were marked by her increasing radiance and my increasing invisibility... served only to increase her power over me.
Repetition on "increase". The first two are good, but I was pointing out the last one. Use a synonym.
[/quote] my subconscious took over and I began to fight back [/quote]
Just curious on this one. Irina is your imaginary friend right? Wouldn't she be your subconscious? Or are you saying that you were fighting back against your subconscious, which is Irina?
That is pretty much it. This is a very strong essay and even though it is long, it keeps the readers attention. You could try and cut it up a bit and make some parts more concise, which I would try to do. You're at around 950 words right now. I would try to cut it to 800ish if possible. Personally, I don't think it's too big a deal. But if you could keep your voice and passion in a more concise version, it would be stronger.