"We are the Ylikith, the despised ones. We wanted to destroy life and recreate somehow in our own image, but the pesky Precursors took that away from us..."
The Ylikith were an ancient race of dark organics. Eons before the creation of the Edanians, they became extinct, but they returned during the Chimeran Civil War. Their purpose was to destroy all organic life and recreate it in their own image.
The Ylikith and the Precursors have fought in many wars. Those wars were always started by the Ylikith, who wanted to destroy all of organic life. They nearly won the final war, but they became extinct when the Precursors wiped them all out with the Primordium. During the Ylikith-Precursor Wars, they destroyed major sections of the Multiverse not known to today's species.
Return from the Dead
One day, a group of Edanian scientists entered an ancient Precursor temple. It was the first temple discovered. As they roamed the temple, they approached a mysterious life preservation chamber. Inside it was a group of Ylikith individuals, who were preserved from being erased from existance, and hopefully in the future they would not be evil. When the Edanians opened the chamber, Ylikith with weapons mysteriously came out, suggesting that they were released before time. All of the Edanians in that group died, and the Ylikith released their other brethren.