Eclipse's unleashed demon. Eclipse let Equinox free from being sealed inside him, because Eclipse realized why Equinox was so angry at him. When Equinox was first free, he looked almost exactly like Eclipse, other than the eyes, tail, and mouth. After a while of talking, they both decided to change Equinox's design so no one would confuse one with the other. This is what Equinox looked like after the design change. His tail and eyes are still the same though.
#eclipseandequinox