Strings of Fate, Griffin and Serpant

When a spell backfires Harry is given a choice in how to work his thread back into the tapestry of life. He chooses to let the tapestry decide for him and is sent back to the battlefield,with no memory of the tapestry. He is surprised when Snape is found, alive and somehow a teenager. However both Harry and Snape begin to remember their past lives, as Godric and Salazar m/m