Significance of Barlow's Letter

When Mark, Ben, Jimmy, and Father Callahan go to the Marsten House to kill Barlow, he is not there. He has left a note for them. It is a rich vellum sheet in a matching rich yellow vellum envelope. Barlow has written it with his own hand. His handwriting is described as being "an elegant, spider-thin hand." He addresses the group as "My Dear Young Friends." He uses cordial, polite language throughout the letter, speaking to them as if they are guests. Barlow addresses Ben directly in the letter and tells Ben that he has left the vampire Susan there in the basement for Ben to destroy. Barlow then speaks directly to Mark in the letter, telling him that he caused him to kill Straker. Barlow wants revenge for having lost his faithful servant, and he writes that he will destroy Mark's parents and then kill Mark. Barlow writes to Father Callahan, telling him that Father Callahan will end up undoing himself. Near the end of the letter, he addresses all four of them once again by name. He has even anticipated that Jimmy Cody would be there.