John + Smoke Monster

back in season one-ish john locke was the first character to see the smoke monster

in later seasons the smoke monster takes the form of an influential person in the viewers eyes
mr. ecko saw his brother
ben saw his daughter

i think that this interaction played a huge part in john’s devotion to the island.

So my big question is what/who did he see?

I think it’s safe to assume it wasn’t his father, because his father appears later to his surprise and he has him killed.