Hey,
On the first line you repeted "that" twice.
Anyways i enjoyed this poem. I liked the emotion youve placed in it.
The structure could be improved in this though. Try making each of the lines the same length? It'll just look better to the yes at first glance. I know it shouldnt matter but it does. I liked your discription; "vicious demon" you can kinda see this demon in the minds eye. Butthis demon is inside. Very meaningful. Then you describe how your fighting this demon. Rather then sad i think this poem should be in Life catagorie, as your fighting it. Very inspirational if you ask me. I liked the end, im glad your not hletting him conssume your soul howveer bad it gets. :) Anyways punctuation, well its good but keep using it and itll keep improving. Just read it aloud, where do you want a pause? Where do you want it to speed up? And in the end of the poem your punctuation kinda feel again. Lol, just write the poem first then put punctuation in it. Not your best poem though. Keep writing. xx