Spinel is the main antagonist of Steven Universe: The Movie, as well as a supporting character in the limited series; Steven Universe Future. She was Pink Diamond's playmate who was abandoned after she went to colonise Earth and start the rebellion. After waiting for 6,000 years, Spinel decided to get revenge against Steven and the Crystal Gems.
What Made Spinel Redeem?
Spinel waited for 6,000 years, and then she started to redeem into a villian, but she learned a lesson after she turned into a good person. and spinel did became friends with steven in Steven Universe Future. Now, spinel is the most famous character after Others Friends, and being a good person.