In the sequel to Allegiant: Alternate Ending we see that 16 years has passed since Tris and Tobias found Will's crib empty. Tris continues to struggle at coping with the loss of her son even after all this time.
Through this story we also see the struggle one person has trying to find the missing piece to the puzzle that they have yet to complete.
Reminder: Veronica Roth owns Divergent. I do not. This was only fanfiction that was inspired by her books.
I decided that I wanted Tris and Tobias to live a little so imagine Veronica's book stops before the war on abnegation and things stay normal. Skip a couple months on and my story begins...enjoy :)
All rights to the fabulously talented Veronica Roth