Twilight's Changelings: Two Vampire Novels

Dark Changeling: Psychiatrist Roger Darvell suffers from a dark thirst-and a very strange midlife crisis. At the age of forty, Roger discovers that he is no ordinary man. He also learns that vampires exist and that a few of them kill as wantonly and cruelly as any monster in a horror film. When a homicidal vampire follows Roger from Boston to his new home in Maryland and attacks one of his patients, Roger must come to terms with the truth about his heritage.
And he must find a way to destroy the killer before his newfound lover becomes the renegade's next victim. Child of Twilight: Roger Darvell's contented life with his psychiatric practice and his partner and lover, Britt, suffers a shattering blow when he's confronted by his twelve-year old, vampire-human hybrid daughter, Gillian. He sired her by artificial insemination and never expected to have a relationship with her.
In the throes of vampiric adolescence, overwhelmed by the urges and powers surging through her, Gillian runs in panic to the half-human father she has never known. But a rogue vampire, pursuing revenge on Roger for her brother's death, kidnaps Gillian and offers to teach her how a "real" vampire lives-and kills.