In Time and Again, the search team finds Janeway's and Paris' combadges and notes that the combadges were caught in the explosion. This implies that there must be (or have been) some reality in which Janeway and Paris are present before the explosion but do not prevent it.
What's the story of the Janeway and Paris who are there before the explosion but don't prevent it? At what point does it diverge from the pre-explosion story we see? And how?