I really liked how you brought the different traditions and mythologies together. The concept of the heriot was very much in the Harry Potter tradition and created a believable need for Harry to confront Voldemort and the Death Eaters again. Your characters were all great, from the canon ones to the originals. (Loved Ratatosk!)
It was sad when Harry had to trap himself in order to save his son and to stop Voldemort, but he did get Severus (and his parents and other loved ones he'd lost).
I really got wrapped up in this world you created!