Sadness is one of Riley's emotions that are introduced when Riley cried as a baby. Whenever she touches a memory orb, it turns blue. Sadness is eventually seen with her friend, Joy about collecting memory orbs into the internal core. When all the internal core orbs have been scattered, Sadness and Joy go after them and end up going into Long Term Memory.
While trying to find the important orbs for the internal memory core, Sadness and Joy were distracted by an imaginary friend named Bing Bong. He guides Sadness and Joy across Imagination Land and they try to return to the headquarters by taking the Train of Thought, but are unable to reach it when Riley's Honesty Island begins collapsing and derails the train.
When Joy finds a recall tube that sends memories to the headquarters, she gets in, but finds out if Sadness got in, the core memories were going to get sad. Joy, with no other choice, disowns Sadness and tells her that "Riley needs to be happy"; the plan however backfires when the tube is fractured, causing her and Bing Bong to fall into the Memory Dump. After Joy feels empathy for Sadness, the two manage to finally make it to the headquarters when Riley is leaving San Francisco, an idea hatched by Anger. Sadness was able to save Riley by removing the idea, and instructing her to return to herparents, causing her to reveal her personal thoughts about her new home and how she misses her old one, which her parents share as well. This ultimately negates the ordeal that Anger caused. By the end of the film, Sadness and Joy reconciliate and the emotions begin to help Riley adapt to a new life.
Powers and Abilities
As an emotion, she is in control of Riley's sad mood.
Sadness Manipulation: She can program Riley to turn sad, when at the controls. She can even infect the environment as she turned a cloud into a rain cloud.
Memory Manipulation: She have the uncanny ability to turn memories into sad memories.