Snape did teach Harry and all us readers once again that a person is neither all good nor all bad...just like James, and even Dumberldore everyone has a reason for lashing out or acting out and everyone has the ability to make a bad choice like Dumbeldore did as a 17 year old and james with teasing Snape the question is do you keeping making bad choices or decide to do good as james and Dumbledore and Snape....