Sorry, i was drawing. And you didn't miss me~
Alright, so Cosmos is of a race known as Celestials, which are basically made of the same impetus of energy that creates new stars and new worlds in the universe. Unlike that energy, they are self-contained. They do not burst with energy, but instead have a long slow burn, with occassional short bursts of brilliance. These short bursts, when in contact with other living things sparks a chain reaction, or inspiration.
So, Cosmos is a good Muse...
On a personal level, Cosmos is gentle, friendly, easy-going and relaxed about pretty mcuh everything. He's seen so much and experienced so mcuh that nothing really phases him anymore. That said, he's still very intrigued by watching the myriad of ways the same events can unfold depending on the time and people involved.
In Appearance, all Celestials look different. I'm not really able to show it, but Cosmos has a shimmering shifting skin hue of champagne pink. His skin actually sparkles a little as if it were covered in eyeshadow or something faint like that. Every Celestial has some planetary body in them, for Cosmos it's his Solar Eye (for Galatea it was her Super Nova Heart) as well as their universal matter, or nebulae - for Cosmos it's the six wings. These wings are also in a constant state of flux which is altered by his emotions and intensity of focus.
Yeah...what else would you like to know?