Why is there another male dog following the alpha?

There have been a pack of dogs near my location for months I see them every day. Every so often I see another dog enter thier territory and they go crazy, barking and driving off the other dog(s). Until like a week ago I see this blonde dog following the alpha everywhere and I mean sticking to him like glue no more than two feet apart. I'm pretty sure in the past I saw this blonde dog get chased off by the pack. So why is the alpha not chasing it off now and letting him smell his rear end and stuff? I also observed for the first time today that the blonde dog stopped the alpha from chasing off another intruder, the blonde dog just trotted in front of the alpha without barking and didn't let him pass. What was that about? Is the alpha losing his position?