Who is Tommaso, Dante, and Marcus Notte from A Bite to Remember and what is their importance?

Tommaso, Dante, and Marcus are Stephano's immortal cousins that come out to help with the case and take care of Stephano. They too are very tall and Italian and Tommaso and Dante are twins.

More: http://www.bookrags.com/studyguide-a-bite-to-remember/characters.html