Of all the categories and genres in HP fanfiction, I find that the Historical genre is one with a lot of potential which doesn't really get explored much. So I was pleasantly surprised when I found this sonnet from the Grey Lady's perspective. I find her a very fascinating character, personally, and found this a very interesting poem, to say the least.
When I read the poem, I could place this as the thoughts going through her mind as Harry calls out to her during the Battle of Hogwarts. It fits there so well, especially the first line where she questions "Who wants to speak with unimportant me," as though surprised that someone is calling her.
The poem starts off on a strong note - Helena Ravenclaw does not come across as a person who is regretful here, she comes across as someone who is still strongly opinionated about events - someone who hasn't been blunted by the blades of time. She is still a disappointed woman - disappointed in herself, more than anything else, and angry. She doesn't try to justify her actions, instead, she accepts them whether right or wrong and thinks it over only from her perspective. I quite like how you picturise her; it ties in well with canon, and still gives her a fiercely individualistic streak that I can appreciate.
I enjoyed your take on the relationship between the Lady and the Baron. It is her view, no doubt about it, but I like how you seem to have brought about a kind of rift in the relationship right there. She may feel it is her fault at the time, but it is definitely indicative of the problems that existed even before drastic measures were taken.
In particular, I liked your word choice at points. 'Uncontent,' not 'discontent', being a good example of that. It sort of adds to the feel of a poem based in the past? I think so, certainly.
Rowena Ravenclaw's description also really agrees with my picture of her. Helena seems to want to be like her mother a lot. We can see that she, in particular, takes note of the posture, and we can see in the books that that is how the Grey Lady is, as well. It is in those lines, actually, that you really bring out a lot of Helena's character. There is a sense of regret coming into the picture, and there's also a strong exclamation at having been denied the chance to speak to her mother about the events that took place. She seems a little angry behind her very stoic demeanour, in my opinion. A daughter who wanted so much to be like her mother, a daughter who felt responsible for the death of two, a daughter discontent with the life she led and one with no means to correct the mistakes she committed. I like how you have brought that out - before you speak of the mask, or the veil, as you call it, I can see her true emotions.
The ending seems to have a touch of finality to it. To me, the veil has a significance in two ways. One, as you directly put it, it is a mark of disgrace, and second, it also kind of puts back all the emotions that had come to the fore in the lines above into a mask of calm which cannot be penetrated that easily. It just struck me as that, when I read the poem, and I thoroughly enjoyed it.