Story centered on Nymphadora Tonks
She is a junior auror.
This story starts way before the fall of the Ministry.
She has already met Harry Potter.
Eventual pairing: Nymphadora Tonks/Harry Potter
She witnessed some strange phenomenons/activities/events that she can't rationalize and that leave some shimering residue that very few people notice and less remembers. A few times she kind of notice someone that might look like the Boy-Who-Lived, Harry Potter, but older, more mature and self-assured, ... different(?)
And it happens again, and again, and again until one time she gets "there" early enough to intervene and gets sucked into it. She gets recruited by the Unspeakables and gets to work with Time. She gets to work correcting Time, events, History. She help prevent several catastrophies happening.
One day she meet a man her age that recognize her as one of the most successful timeauror (timecop) ever to live and he needs her help to prevent a big one. A dark haired green eyed young man, Harry Potter.
He came in the past just as she asked him later in her life.