I don't remember the name of a Edward/Bella Twilight Fanfiction I read years ago.

In the first part of the story, Bella goes to save Edward in Volterra (New Moon); after which they both return to forks, alone for a while, where Edward changes Bella, and after a few days the rest of the Cullens return too.

I remember the Sequel of this story better.

In its Sequel, the Cullens have moved to England, where they are invited to a party/ball hosted by an acquaintance of Carlisle, a rich influential vampire considered royalty in England by vampires.

At the party, a Prophecy is hinted at regarding Edward overthrowing Volturi and ruling volterra with Bella by his side.

Some days later, Alice sees a vision of a banner with a lion swaying in Volterra - the fulfillment of the prophecy.

After which events happen, leading to a war with the Volturi, where the Cullens are aided by that royal vampire and his mate - who is beheaded in the battle, but is revived afterwards... and the Cullens win the war.