Well done! I was sucked at once into this world and these characters. The cane story is beautifully-conceived, and you do a fine job creating the contrasts between Severus's world and Lucius's. Given the backstory as you set it here, It's easy to understand how Severus is led initially to Voldemort.
That scene in the park is particularly poignant, reminding us as it does of the canon depiction at the same time that we're seeing the park's current decay and emptiness. The James/Lily moment is a killer; however righteous Lily's anger, we can see just how her behavior would cut Severus and send him further toward darkness. (That picture of him swinging and scuffing his shoes -- so revealing of so much about him, how there's still so much of the child in him at the same time that he's rapidly becoming an adult.)