Haunting Four (A Divergent Fanfic) (After Allegiant) (Completed)

This is the sequel to Fixing Four that I wrote. This is another after Allegiant fanfiction.
After death, Tris haunts Tobias every day and watches over him. It's been like this for 2 and a half years until Tobias attempts to commit suicide. She somehow ends up trapped in Christina's body after saving his life yet Tobias doesn't know it. Will Tobias find out who she really is or will he continue to suffer the loss of Tris?
Also in this book the factions still exist but are not active.