An interesting picture of something away from the main Harry Potter storyline. I always thought Hestia was much older (she fought in the original order at least sixteen years ago) but that does not matter for this particular one-off.
It's interesting how I've always pictured Hestia as someone Sirius and Remus' age instead of someone Tonks' age. That small difference made the story much more interesting because I was looking at Hestia quite differently than I normally do. I'm glad she's so close to Megan (who wasn't listed in OotP as being one of the DA members) because positive family ties are very important during difficult times and the two sisters know they are coming... even if their parents are trying to deny that they aren't. Well done. I enjoyed this chapter immensely.
Another cracker! I am really enjoying your exploration of different characters, hanging off the Christmas theme. You prose is very descriptive without being too flowery, and your characters are very authentic.