3. "This Is Not Meth." (Season 1, Episode 6)
After specifically stating that he would have no involvement in the distribution area of the crystal meth at the beginning of an episode, Walt finds himself left with no choice but to approach the territory's meth dealer, Tuco Salamanca, by the end of that very same episode. After Jesse's unsuccessful attempt to unload his and Walt's meth to Tuco leaves him severely beaten and hospitalised, Walt takes it upon himself to get the job done and things get interesting. After being patted down and discovered to have nothing on him but another pound of the meth, he is allowed into the building. He has the balls to walk up to Tuco, a man who spends his spare time sniffing rocks of various drugs off a hunting knife, introduces himself as 'Heisenberg' for the first time in the show and not only demands that Tuco pay for the drugs he stole from Jesse, but give more money on top of that to compensate the beating he gave him. Tuco doesn't take this very well and gets a bit shouty about the fact that he's just battered Jesse and Walt must be dumb to think he can waltz in there and ask for the money for everything, whilst bringing another load of meth with him. Walt then picks up a rock of the "meth" he has brought with him and says: "This... is not meth." He then turns, throws it into the ground, and the whole floor of the building just explodes. Windows taken out, air conditioning units blown off, the lot. Inside, Walt picks up the rest of the bag, threatening to throw the rest on the ground unless he gets his money. Tuco gives him the money and agrees to accept a delivery every week. It turns out the "meth" was actually fulminated mercury, an explosive chemical compound. He walks out of the building, money in hand, through the confused gangs of people outside and back into his car, where he checks the money and has a celebratory, adrenalin-fuelled "get in there!" moment, as we all would in that situation. It's truly the beginning of the Heisenberg character. That's the beauty of the scene, the introduction to the notion of Heisenberg. Even Walt looks scared of what is happening to him, spending almost the entire scene in fear after the explosion. Up to now we've just seen Walt be a fish out of water, somebody who seems like he genuinely doesn't want to be in the situation he's in. Now he looks like he's adapting to it, as if he's beginning to enjoy becoming this new persona.