Built before the death of the world. He continues on after everything died. No-one knows who built him or when. No-one knows why he just travels the world. No-one understands how he is still running. All they know is he wishes to maintain the appearance of a generic red fox. And will do so at a higher priority than most repairs to his body.
He is often found with missing limbs or holes in his body. Only stopping to replace them after the black "fur" is reapplied to his tail, legs, arms, and ears. The "fur" is really anything black that will stay on his body. Dye, Paint, Ash, Coal, and everything else. He will even make a white spot on his chest and neck if he finds any white to do so with.
He is exceptional at repairs. While this is because of his time fixing himself, or if he was programmed like that still remains a mystery. He does seem to be able to find metal and wires in piles of discarded material and can form them into usable shapes. If he has access to tools, he is known to use them. But most of the time he just hammers bolts with his hands and bends metal with his weight.
He has never been seen completely immobilized. He seems to not want to stop with his travels. So he stops for major repairs like both of his legs broken and other larger-scale issues. His travel patters seem sporadic. Sometimes going in a single cardinal direction for weeks on end, just to turn around and backtrack for nearly as long. Though he has gone back to previously visited junk piles to replace limbs. So we can theorize that he has a strong memory and sense of direction. But that only adds to the confusion of his travel patterns.