Dragon's Last Stand?

Setting: After the grand magic games and Tartarous. But in this story the guild did not disband, but natsu still went to go train.
Summary: Lucy has left without a trace and the only one who knows where she is, is gramps. What is Lucy's connection to the dragons, and is there a dragon worse than acnologia?
Pairing: stilu
There will be five oc character's.