joseph meeting henry (little bit of spoilers)

[Spikeyroxas]

The way i see it is
josephs apt became seriously haunted which gave him all the headaches. One day (in dream sequence) the hauntings reached the point where a ghost victim came through and killed him (becoming 15/21) i also thought that through dying he became a trapped soul an merged with his apt. but his stong mind resisted possession so stayed earthbound as a "good" spirit. This is based on my own theories though...)
i also think the only reason the victims attack henry is because they are being influenced by Walter.