Ah, a nice happy ending. Though we still don't really have any idea how she is going to explain him to everyone. Even more so now that he is her fiance instead of just the 'dead death eater'. LOL.

I do like the HG/DM pairing.  There is always something about the 'bad' boy turning good (or good enough for Hermione to like anyway). 

I would say one thing: sometimes less is more.  Even though this is a one-shot, it felt like we were given a lot of information in a very short period of time.  Experiment with different ways of saying things to give the reader information in a leisurely manner. One of the most important things a writer learns is to 'show,' not 'tell.'  In your next story, perhaps concentrate on showing us more.

One of the things I do when I write is when I am finished, I change hats.  Then, I read it as if I were not the one who wrote it.  I detach myself from it completely and pretend I am one of my readers.  It is not easy to do, but it is a great thing to learn if you can do it.  This is where you can catch all those areas that perhaps rush a little or don't give the reader enough information.  It's a tedious process, but I know you have the determination to stick with a story and work it to be the best it can be. 

This was a very fast-paced story. I do enjoy the HG/DM pairing at times. I think it's nice and fluffy for the Christmas season. In the future when you write, maybe you could take a bit more time to develop the relationship more slowly and the also characterize your characters. I do realize that it's a one-shot and intentionally quick. Just a suggestion for any chaptered fics you might have.

I haven't seen much HG/DM pairings, so this is different reading for me. In a good way. The writing was clear and detailed, well written. Any critique I would have given was more or less summed up by Southern Witch's and notsosaintly's comments. Keep writing and keep up the good work.