It's the cabin fever.
At least, for most of us it's cabin fever.
Some (esp. the multi-personality troll) have always been that way & nothing will change them.
Just because Doug lives on his own little island, is retired, and has nothing better to do...
You'd think a man of his age would act more civil rather a 12 year old who hasn't hit puberty yet?...then again, maybe it is his senility.