Bezoars of Yesterday and Tomorrow
Hypothesis: Vampires are capable of vertical inheritance.
Finish knocking Jasper up, for the third time. Why? Because a story is not complete without a parity for Jasper.
Knock up Emmett and Rosalie too. Why? Because it's their way of dealing with the loss of a child.
Rebuild vampire society after the war, including the transition to an egg-laying society and the adoption of eggs that were orphaned by the war.
Move the Cullens back into human civilization and send the kids to middle school, so that they can learn to interact with humans and blend in.
Send Masen to speech therapy with the humans so that he can learn to talk.
Send Jasper back in time, with the aid of his time-traveling twins, to meet his human family and resolve any lingering issues he still has from his convergence.
Accuse Jasper of being sexually attracted to his grandmother and bring up this accusation as many times as possible. Why? Because it's the new running gag.
Make entire story one hundred percent biologically accurate, despite the vampires.
Tell a bunch of Cullenesque stories and make it funny, because that which is funniest is best.