Ontera, A fantasy world full of forests that has a large number and variety of sentient beings.

Sarinia was born to a clan of her species in the Ekar forest. The Ekar forest was a place where her clan fed mostly on a species that they cohabitated with. In this place Sarinia laughed and played, being taught that showing your emotions, whether they be positive or negative, is a good thing. Although this typically creates a very broad emotional spectrum for most, Sarinia tended to stay towards the more positive side of the spectrum, generally being a happy child.
When Sarinia came to be 25, she went through a coming of age ritual amongst her people. When one of her clan turns 25, they are given a siphoning stone and are to make the stone cycle through the emotional spectrum evenly. Until they manage that, they are not considered to be a adult. Sarinia had throughout her life tended to stay around people who were happy, avoiding negative emotions. The ritual forced her to seek out those with negative feelings and get used to feeding off them.
When Sarinia became 30, she went out to explore the world as some amongst her species do. On her travels she had to fight some who would try to eat her, but found love amongst some other species as well. She found an interest in learning what makes people of different species and cultures happy. She fell in love with a member of a short-lived species, having a child and staying there long enough to see her children from that union grow up, grow old, and die before she could no longer take it and vanished. She made a promise to from then on try to keep from falling in love with those who would live a much shorter life than her.
She went back to her village after 7 years of being away, and was going to try to settle down with someone of her own species.

Changes colors based on the type of emotions stored in it. Anger would be red, fear would be yellow, sadness would be blue, happiness would be green, and love would be purple. In most cases it would shift between those colors, staying the longest on the color of the emotion it has most of in it. The gem can at most hold 100 kilos of shape-shifting worth of energy, however, retrieving energy from it is slow, at a rate of 1 kilo's worth in 3 minutes.