My King A Caius Volturi Fanfic

Athena stone and her twin brother axel stone are both original vampires they were the first ever vampires in history other than the Volturi their parents were killed during the witch trials and have been on their own since then but then a few centuries Carlisle found them and helped them and then created a family but when they had to leave forks because people started to see that they weren't aging but now have to go to Italy to save their and Alice adopted brother because he was left broken without his blood singer and who was supposedly 'dead' but what happens when the twins meet their mates during their trip to Italy? what will happen? well read to find out.

p.s. this is my first story so idk but hope you like it I also used some of my own OC's and no this no a the ballad of songbirds and snakes and twilight crossover I just used them because I thought they would be good