From what I can gather, "a ratman inhabitant" is this construcs PH. After killing the obliterated, this was the only thing to spawn. It may not be the only possible PH, but it is a mob I have seen quite often in the graveyard area. It wanders the same path as the obliterated construct as well. I will post other PH's if I find there are others.
Pants seem to be the rare drop btw.