Why do the poeple who you can meet in sovngarde disappear when the mist clears.

Ulfric, Galmar, Torygg and Froki where in Sovngarde but they disappeared except for Froki.

When ya gotta put (possible spoilers) in the subject. It probably doesn't belong in the forum where at the top it says, Do not post spoilers in this forum.

it isnt exactly a spoiler, its just so nobody moans at me.