Griffin's journeys
Note that in the last scene, in the diner, J and K were talking and Griffen was not there aside J. it was clearly someone else, with about five empty seats between. Then after J and K leave, Griffen appears, and breaks the fourth wall. K comes back in and comments to Griffen, seemingly not knowing who he was.
Note that Griffen hasn't aged, or changed clothes.
Griffen must be traveling through possible realities and time.
It seems like K does not recognize him. That's a big, complicated matter, for another thread.
It always intrigues me, how some characters can break the fourth wall and it seems to work, although it risks bursting the bubble. I think it either shows the stature of his character, or it implies that our world is just another possible reality that he can join at any time.
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The story is king.