I really enjoyed this! Loved the mystery of Snake!Snape and that you made Snape just as bitter, nasty and difficult as in canon, making Harry really work on his own patience and tolerance before they began to relate to one another. I liked the way you didn't have Snape cure himself - he's human and his potions sometimes fail - and I loved that Harry came to accept him as he was.
The drawings are great, loved the details, especially the flowers, and Snape's scaly skin and his desolate expression!