User:SOTO/Forum Archive/The Panopticon/@comment-26285319-20170104192003/@comment-1350697-20170105153336
From Tardis Wiki, the free Doctor Who reference
The obvious difference is that Ground Zero isn't a separate entity like Shalka is, but the then-latest story in DWM's ongoing series of comics serials.
In the "forking timelines" metaphor, Ground Zero is part of a full prong on the fork, that eventually connects back into the main timeline, whereas Shalka is a little nubbin on the side that derives from the main timeline but doesn't connect back to it.
...Makes a lousy fork, this.
