Undertale/Good Route

The good route of Undertale, most commonly referred to as the Pacifist route, is the one in which the player resolves each monster encounter without taking a single life, thus winning the trust of the Underground and, ultimately, allowing them to migrate freely back to the surface to start a new life. Along the way, you end up hanging out with each of the main monster characters, getting to know their personalities and backstories.

Unmarked Spoilers May Appear

''""Ah, the barrier's open...? You know I cannot move. Why are you telling me? To mock me? Everyone may think you are a good person, but this snowman knows the truth. Someday, your friends will realize your heart is as cold as my butt."" ''
 * Bitch in Sheep's Clothing: Yes, it is possible to complete the Pacifist route while generally being a dick to everyone; as long as you don't kill anyone (or leave them for dead, in the case of Undyne), you can be as horrible as you like. Surprisingly, won't call you out on your douchebaggery.
 * That being said, there are two minor characters that will call you out in the Pacifist Ending sequence.
 * If you simply stood around without doing anything while Monster Kid was hanging for dear life from a bridge, they'll remember how you just sat around and watched them almost die. If you try talking to them, they'll stammer for a bit, before quickly telling you not to talk to them, and remain mute afterward.
 * If you had previously eaten the Snowman Piece in front of the talking snowman, he'll have some harsh words for you:
 * Body Horror: The Amalgamates in the True Lab. Up to dozens of monsters, injected with Determination, now sharing a same body in an attempt to hold some physicality.
 * Driven to Suicide: ended their life to enact a grand plot to kill the humans and reclaim the surface world for the monsters. But what you may not know is that ... We can only guess at what could drive someone to such desperate measures.
 * Freaky Miniboss Squad: The Amalgamates.
 * Hello, Insert Name Here: So, remember how we said this trope was subverted in the Neutral route? It turns out there's a reason for it. . It's all a bit Mind Screwy.
 * Love Letter Lunacy: The subplot where you help Undyne confess to Alphys involves bringing such a letter to the latter's lab, but Undyne forgot to actually sign her letter, so Alphys believes the player wrote it and immediately agrees to a date. Hilarity Ensues.
 * Self-Sacrifice Scheme/Thanatos Gambit: What original plan was revealed to be in the True Lab Tapes.
 * Wham! Episode: The True Lab Sequence. The reveals in this part, in rapid succession: Alphys' experiments with a substance extracted from human souls she calls "Determination", the existence of the Amalgamates, the truth behind the death of the Fallen Child,.