Thank you so much, lesyeuxverts, for the lovely present!
I really like this AU-- to go without Harry until after the fall of Voldemort, because of the snake in the zoo is an excellent conceit. You evoked the personality of a person who has spent 10 years as a snake rather beautifully, I thought, and your Snape is marvelously in character.
Pythios is a convincing magical snake. I don't recall many animagus stories where the animal form has access to so much of the wizard's magic-- I loved Pythios vanishing his cage when it suited him, and carrying his heat lamp around with him. And the scene where he helps Snape with the potion, holding the stirring rod with his tail, is wonderful. Perhaps it will inspire a fanartist out there?
I think I'd like to see more stories in this AU; it seems to be potentially a rather happy one and a good setting for all kinds of fluffy stories like this one. I'd love to see this world's Remus and all the potential for explosive family drama, with happy endings of course.