I haven't taken the time to read back through the old theory threads here so I'm not sure if this has been postulated before; but I wonder if Randy perhaps was Roberts former employee and later his replacement after Robert's arrest?

CJ says to send 'Randy and the other techies' to the water works when pressure was lost early on. By stating Randy first and the 'others' it sounds like Randy is the leader of the techie group and perhaps the smartest one among them. Perhaps he was Robert's #2 in charge. When Roberts was arrested Randy took his role at work at Raydon Labs. When all crap broke loose and both were turned and saw eachother again Ink wanted Randy to fall back in line as his #2, but Randy has spent the last year or so as the head man in charge and wasn't ready to take the back seat again. Ink tries to force the issue by tattooing Randy, who then takes off from Ink's group and some of the other biters and little ones follow with him.

Maybe be this is why we also see the little one attacking the other biter at ground zero? Crips and Bloods of the zombie world so to speak?

I'm not sure I'm 100% sold on my own theory yet, but it definitely has the wheels in my head turning