* Their childhood friendship: Snape revealed that he and Lily were close friends in their youth, sharing a love for magic and a disdain for bullies like James Potter. He even confessed that he called her "Lily" despite her preference for "Evans."
* Lily's rejection of Snape's dark path: Snape revealed that he was drawn to the dark arts, which ultimately drove a wedge between him and Lily. She rejected his friendship and his dark leanings, which fueled Snape's resentment.
* Lily's love for James Potter: Snape revealed that Lily fell in love with James Potter, despite his bullying tendencies. This further fueled his resentment and envy.
* Lily's sacrifice for Harry: Snape revealed that Lily died protecting Harry, her sacrifice being the only reason Voldemort couldn't kill him. This act of love and sacrifice was the reason for Snape's loyalty to Harry throughout his life.
* Lily's love for Snape: Snape reveals through his memories that Lily still cared for him. He remembers her saying that Snape would have been a good wizard if he hadn't gone down the wrong path. This suggests that Lily still had some love for him, despite their falling out.
While Snape was often harsh and critical towards Harry, he always held a deep love and respect for his mother, Lily. His actions throughout the series were driven by his desire to protect Harry, and his love for Lily was the driving force behind his life's choices.