[Ravager]

Seeing as I didn't say it in the first post, welcome to GB, jack.

You could either go down the fantasy route with something maybe similar to Lionheart or you could go to the sci-fi route with something like Stargate. There seems to be less sci-fi in this area, so that could be a good direction to take.
I can give greater descriptions of either if you haven't seen either Lionheart or Stargate.

There was a plot in Stargate SG-1 (that follows the Stargate film) including a 'Quantum Mirror' which would supposedly link to a different mirror in countless different realities. These would all have branched off at a certain point due to a different choice somewhere along the line. Anyway, you could come up with something pertaining to exploration/aiding other realities througha similar device.