| This prologue began in monotony. This is because a lack of varying sentence structure. By that, I mean constructing sentences of various lengths and styles. Without variation, a story lies like a stale sea, despite whatever grandiose plot and whimsical language you have.
You can fix that by combining the first two sentence. The first three "paragraphs" even. Fixing them, as a matter of fact. No adverbs, first of all. Painful suggests slow, anyway, so show us her pain, and you kill two birds with one stone. And, one second, she had just painfully sat up from her bed, and the next she's at a window. You not only made a sudden jump, but you just threw away a great chance to show us her struggle by showing us struggle to get to the window with its wonderful red light. No show, no flow.
You don't flow steadily from one paragraph to another, which are what paragraphs are for: to direct the flow of a story. The first step to doing that is indenting, which you didn't do. About 80% of this story is one big paragraph. Without the organization indenting grants, one can get lost easily.
And it was in that very paragraph that the most problems were in. 2/3 of that huge paragraph is a run-on quote. You began the paragraph with a quotation mark, but, with jumps from dialogue to narration (which is improper in itself) you didn't officially end it until 2/3 of the paragraph. And, even then, in narration, you jumped to either what I would call dialogue or stream-of-conscious narrative. One needs quotation marks. The other needs italicization. You figure out which one you meant.
Also, some narration is superfluous. "Another" and "again" both suggest that the subject is being continued. No need for both. Add that with the lack of contractive dialogue, and the fact that Shenna is so descriptively and figuratively recalling such a traumatic event, and it sounds pretty unrealistic.
Subtracting items add much more. Make the memory more vague, at least to the audience. Don't have her recall it so descriptively. Emphasize her struggle by having her fight the memory. Change the way you go about the entire paragraph.
Found a paradoxical sentence, too:
Even though I am immortal I can still be killed and if wounded badly enough I could die.
The second clause disproves her immortality. Therefore, she has none.
Also, "the sweet sent of blood" should be scent. Don't know why it would be sweet, either, unless Shenna's a vampire.
I liked the figurative language but that's about it. There's potential here, though. Consider what I said.
P.S. Is "Day of remembrance!" the title of the prologue or the real first sentence? If the former, remembrance needs to be capitalized and the title needs to be separated.