Hair: Black, the style is basically Little Boy Hair, except a bit overgrown
Eyes: Black (use a really dark gray so that you can still see his pupils)
Height: 4'8" (142 cm)
Build: Normal little kid
Signature colors: Black, wears whatever people put him in (generally darker, cooler colors)
Story: Asher was an orphan who lived in the Twilight. Unknown to him, he'd actually been taken there as a baby after his parents were killed. Sound, a strange masked man with only one arm, had discovered the next black and per his master's orders, killed the baby's parents and dropped the baby into the Twilight where they could keep an eye on him. Unfortunately for Sound, Asher acquired his powers - most notably, he can change into and from a bat at will - and escaped before Sound could collect the boy again for his master. Asher ran, briefly, meeting the sisters Tara and Tabitha on the way, and then before continuing his journey of discovery into the Rainbow Covey, vowed to help set the sisters' lives straight again after Sound destroyed their home because he had stopped there.
Other info: You can canon couple him with Tara, but they shouldn't do anything more than hold hands and sit close together.
His most treasured possession is a blank red book he bought the day his life changed. He draws and writes in it and it was given certain magical abilities by Krikor, the Guardian of the Rainbow Covey. As such, it's impervious to water, if you tear a page out it'll just grow back, and he can use the book to communicate with Krikor.