Breaking Bad is a show about choices and consequences. When diagnosed with stage-three terminal lung cancer, high school chemistry teacher Walter White makes a big decision for the good of his family. Like in chemistry, every action causes a reaction and eventually an explosion, and Walter finds his choices lead him down a dark path. Every scheme pulls him deeper and deeper; his humanity eaten away with each questionable decision. Over time he changes from a good-natured suburban dad to the vicious kingpin of a drug operation.

Heavy is the head that wears the crown. Here are Walter White's most underhanded moments. Obviously, SPOILERS ABOUND. And don't forget, season four is available on Blu-rayTM and DVD June 5th, just in time to catch up for Season Five!

Cook Meth In The First Place

With the odds of his survival extremely low, Walter White dreads leaving his pregnant wife and handicapped son without a means of income. After a chance meeting with Jesse, a former student, Walter hatches the plan to cook and sell extremely potent methamphetamine. With Jesse's knowledge of the criminal underworld, the two team up and find they need to be savvy if they hope to survive.

Lies To Family About Money

When Walter shares the news of his illness with loved ones, relatives and friends offer to help out with his treatment costs. Amongst them is an old flame Gretchen. Now extremely wealthy, Gretchen offers him all of the money he'll ever need. However, he's too proud to accept, and dismisses her offer. Instead, he moves ahead full steam with the plans to cook meth. This requires he get involved with extremely violent and dangerous business partners.

Poisoning Tuco

After being threatened by Tuco, a crazed business associate, Walt and Jesse decide they need to take him out. Rather than shoot him point blank and risk reprisal from his cartel associates, they decide to poison Tuco with ricin. However, he's unable to feed him the poison as planned and is attacked by Tuco. Through sheer luck, Walter and Jesse are able to escape at the last moment.

Allowing Jane to Die

The stress of killing, stealing, and lying takes its toll on the partnership of Walt and Jesse. Walt begins to feel Jesse completely slipping out of his control after he takes up with Jane, a recovering addict who relapses along with Jesse. Walter agrees to give Jesse his share of the money but only on the condition that he get sober first. Jane finds out and blackmails Walter. After caving in and giving Jesse his money, Walter still feels the need to help him kick his addiction. He visits Jesse to find both he and Jane passed out after taking heroin. Jane rolls onto her back and begins to choke on her own vomit. Walter resists the urge to save her and watches as she asphyxiates. Finding his lover dead the next morning causes Jesse to get the rehabilitative help he needs.

However, every action has a reaction. Walter's shady choice leaves Jane's dad grief-stricken. Jane's dad is an air traffic controller. Exhausted and dazed, he returns to work too soon and causes two commercial passenger planes to collide in mid-air, killing all of the passengers.

Orders Gale's Murder

Walter's only foothold in the world of drug-dealing is that nobody can replicate or best his formula. This attracts the attention of local businessman (and secret crime lord) Gus Fring. He hires Walt and sets him up with a state of the art super-lab for the mass production of product. This lab also comes with an assistant named Gale. The two get along perfectly. Gus is another story.

Gus and Walter disagree on issues like murdering children. Gus is cheers and Walt is jeers. As this tension grows, Gus has Gale watch Walter and learn his recipe. Once he has it down, Walter and Jesse will be eliminated. In a bid to guarantee his and Jesse's survival, Walt sends Jesse to murder Gale, a chemistry nerd and karaoke fan mostly innocent of any wrongdoing.

Launders Money Via Car Wash

When his wife Skylar finally learns his shocking secret, she gets used to the money. Too used to it. She insists that she be involved in a business manager capacity. They decide to go along with her plan of cheating a local car wash dealer out of his business. They then use that facility to cover their tracks when asked where all their money is coming from.

Poisons A Child to Get to Gus Fring

In his most diabolical scheme yet, Walter White pulls off a long con that eliminates Gus Fring. His plan is anything but simple:

- Convince Jesse to help him poison Gus
- Steal poison back from wishy-washy Jesse via an innocuous third party
- Poison Jesse's girlfriend's son with a not-deadly poison that resembles a deadly poison
- Convince Jesse that Gus poisoned the boy
- Have Jesse arrange a meet with Gus
- Place explosives on Gus's car during the meet
- Find alternate way of blowing up Gus by placing explosives on an old man's wheelchair
- Blow up the old man and Gus

So, yeah, I'd say Walter White has experienced a moral shift and established himself as an adaptable thinker capable of extreme evil. He's become a cancer himself.