They had raided the ship with a band of pirates. Left behind when the others fled, the humans adopted them and began to teach them a new way. They still had to answer for the crimes they committed, but remanded into the humans' care, they began to learn how to care about others, but, more important, how to be able to care about one's self as well.
Krez often had the chance to sit back and re-think his life. Why the pirates had bothered with his basic needs when they constantly called him a useless lump. Why they didn't just space him like they constantly threatened to do.
And above all, Krez wondered why the Human Hyu adopted him. That was a long time in unriddling. Simple equations like, "You were alone and needed somebody on your side," were a complete bafflement to Krez.
Then there was the matter of punishment for his crimes. He had been particularly useless in the raids, as his former shipmates were fond of pointing out. Frequently. He had not done very much in the way of looting and pillaging, and never the third part of the famous trio. He was mostly there to fill out the threat and do some heavy lifting. Nevertheless, he was an accessory to the crimes.