The loathing tells us the narrative purpose of Wormtail’s inclusion in this scene. It is a replay of a pivotal moment in Snape’s past, something he must and can change on his second chance. Snape and Wormtail were the two people who betrayed the Potters to Voldemort. Now they are faced with a similar situation. A woman is frantic to protect her son from Voldemort. Her older sister has her own twisted ideas about what should become of this son. Snape can choose to protect the child this time. Wormtail feels no regret and neither wants nor gets a second chance. He is banished from the room.
