Walt's descent into villainy throughout Breaking Bad is marked by increasingly shocking acts, but none are as heinous as his decision to poison Brock, the six-year-old son of Jesse's girlfriend, Andrea. This act exemplifies Walt's ruthless pragmatism and the extent to which he's willing to exploit the people he supposedly cares for.

The "Evil Juice Box Man"

Walt meticulously planned Brock's poisoning, planting a juice box laced with Lily of the Valley berries in Brock's lunch at school.

He ensured that only Brock would come into contact with the poison, demonstrating a chilling level of premeditation. The writers of Breaking Bad, referring to Walt as the "Evil Juice Box Man," imagined him injecting the poison into the juice box, highlighting the calculated nature of his actions. 

Manipulating Jesse's Love for Brock

Walt's motive was as twisted as his method. He wanted to manipulate Jesse into believing that Gus Fring, their mutual enemy, was responsible for Brock's illness.

Jesse, fiercely protective of Brock, was driven by rage and grief, playing perfectly into Walt's hands. Walt knew that a heartbroken and vengeful Jesse would be the perfect weapon against Gus.

Brock's Recovery and Lingering Guilt

Despite the devastating act, Brock ultimately survived and made a full recovery. However, the trauma of the experience undoubtedly left its mark on the young boy. For Walt, the guilt and turmoil were palpable.

His encounters with Brock after the poisoning were filled with a visible unease, hinting at the inner torment he was trying to suppress.

The Breaking Point for Walt and Jesse's Relationship

Jesse eventually pieced together the truth, realizing that Walt was responsible for poisoning Brock.

This revelation shattered their already fragile relationship, leaving Jesse utterly disillusioned and filled with anger towards his former partner. The confrontation between them crackled with betrayal and animosity, marking a point of no return for their partnership.

A Shadow Over Jesse's Future

Even after escaping from captivity in El Camino, the shadow of Brock's poisoning lingered over Jesse. Before fleeing to Alaska, he sent a letter to Brock, the contents of which remain a closely guarded secret.

The fact that Jesse felt compelled to reach out to Brock speaks volumes about the lasting impact of Walt's actions.

The Death of Innocence: Drew Sharp's Fate

While Brock's poisoning serves as a turning point for Walt and Jesse's relationship, the death of Drew Sharp, a 14-year-old boy killed by Todd during the train heist, further illustrates Walt's descent. Unlike Jesse, who is deeply troubled by Drew's death, Walt coldly accepts it as a necessary casualty of their criminal enterprise.

He even participates in dissolving the boy's body in hydrofluoric acid, signifying his complete moral bankruptcy.

A Heinous Act with Lasting Repercussions

Walt's poisoning of Brock stands as his most unforgivable act in Breaking Bad. It demonstrates the depths of his depravity and the lengths to which he will go to maintain control. The repercussions of this act reverberate throughout the rest of the series, shaping the fates of both Walt and Jesse, and leaving a lasting stain on their consciences.