(Obviously you would need dogmeat to get this. Possibly a encounter where the door only opens if you have dogmeat).
You see a sick dog walk up to you and dogmeat (dogmeat would be required to get this), and it whimpers a bit, then falls over dead. On the dog is a tracking device on a collar, and you follow it. As you follow it, you come across a ruined base. Dogmeat suddenly acts a bit wierd, runs around in circles, then sits in a small depression in front of the main door of the base. A wierd light seems to play over dogmeat, and then the door opens. you start to look around the base and it seems to be some kind of training ground, however, everything is small, almost for children or animals. As you continue to explore the base, you are ambushed by several packs of feral dogs. After dispatching them, you continue through the base, where you see diagrams on the walls of some of the broken and worn down training rooms showing what looks to be pictures of dogs running through them. After getting dogmeat to go through these (might be fun to see dogmeat jump through, say, a flaming hoop or something), you get to a small room with a large shipping container in the middle. Upon opening it, you see inside is a prototype version of the Canine Power Armor [Mark I]. Obviously dogmeat would get some stat upgrades from this, probably more damage (from metal spikes in the helmet), more speed, ect.
(I really like this idea [I even put it in the General Ideas section], so I made it into a special encounter. Plus it would just look so friggen cool.)
That's all I can think of for now.
