Fate/Rewind

After a Failed Experiment Rin and Shirou From an AU End Up in Their Childhood Body's Two Years Before the Fourth Holy Grail War. Can The Past Handle Two People That are Clearly Overqualified for The War? How Much Suffering Can The Two Inflict Upon a Useless Old Worm? Just How Much Stress will Rin Give Her Father and Mother? And Finally, just How Long Can Shirou Hide The Fact That He Is a Dead Apostle? [Description is Liable to Change]