Mynx has an origin very similar to Synapse's. While attending Paragon City University, she signed up for a Crey project for some extra cash. After discovering her lack of family and close friends, they tested a serum on her that gave her several feline features. In a very Wolverine-like fashion, she went feral and slashed her way out of the lab.
After surviving on the streets through petty theft, she was discovered in Steel Canyon by Synapse. He gave her a second chance and took her on as his sidekick, for which she is very grateful. However, she is still very undisciplined and at times barely in control of her animal side.