You did a good job of working a lot of details from the Harry Potter franchise into this fanfiction. It can be really easy to just include a superficial amount of detail into the story to do the bare minimum of setting the scene and characters, but this particular story read like it was part of the existing world of the Harry Potter universe (albeit a very specific kink subset of the Harry Potter universe ).

For a piece of writing of this length, it felt like the rising action was a bit repetitive (which Harry just repeatedly begging Malfoy not to mistreat him); it would have been great to have a little more variety in their character interaction in the lead-up to what Malfoy eventually does to him.

While this isn't my particular cup of tea as far as kink fanfiction goes, I thought it was a well-written story that really used the source material to its full potential and created an engaging story throughout. Nice work!