A Potion Master's Observance

(Rated T cause of abuse mentions and my own paranoia) Dumbledore sends Severus to pick up Harry from the Dursleys. How will this alter the first book? Harry's abuse from the Dursleys is slightly harsher than what is originally put in the book. OOC-ness from Harry and Snape 'cause they're friendly and stuff. dunno much about the genre... ah well... I OWN NOTHING! nothing!