Diego was born in the Dome, to the Sanches family. The Sanches family wasn't exactly wealthy, but neither did they struggle very much. Mr. Sanches ran a farm, and Mrs. Sanches took care of Diego and weaved baskets. Unfortunately, one day, Diego was seriously injured when a truck dropped several hundred pounds of gravel onto him.
It was all they could do to get the boy to a medical centre. In order to save his life, the Republic spliced Diego with Other genes. He was eight. Being separated from his family at a young age never sat well with him, and caused him to become a lot more withdrawn and quiet.
He was spliced with a bird Other, and now has red streaks in his hair, and two reddish brown wings. Once, he could fly, too. He was passed from handler to handler for a while, until eventually he was assigned to a Beta Prime by the name of Angel Gonzales. Ultimately, Diego decided he couldn't stand Angel, after many years of tolerating his abuse, and moved himself to a nice spot under a bridge in Pyxis.
Angel didn't seem to care.
While he was there, he built himself a makeshift home out of a wooden palette and a bunch of cardboard boxes and spare squares of glass. Angel eventually had him fighting in the HoloArena every other day, but he managed to find and save a small cluster of Others, many of them insect-like, a couple not-so-insect-like. There's Jade, Pixie, Opal, and Sapphire.
He and his little team of Others have been making a living for themselves under that bridge in Pyxis for about five years. Unfortunately, however, all things come to an end, and Diego nearly lost a fight in the arena. One of his wings was cut off, but while he survived and the infamous Suyis Lucain came to his rescue, his wing wasn't able to be reattached.
He's been healing, and somewhere in there got a new handler. He's still not entirely sure what to think of him yet.