This is a beautiful story! My heart just broke for Percy when he talked about how things went wrong in spite of how hard he tried to follow the rules, and how he could never achieve greatness--so much like how I see canon-Percy. I've always thought that he was treated pretty harshly by his family and the narrative when he was, from his point of view, trying to do the right thing and protect his family. So it was wonderful to see him finally find someone who appreciates him and sees him as someone special.
I really enjoyed the way you expanded on Viktor's character too, with his competitive streak and his family history. It felt like a natural outgrowth of canon. Oh, and I'll echo songquake's comment that I really want to know more about Garrum! ;-)