WARNING: CONTAINS SPOILERS FOR THE TRAGIC SILENCE SERIES
The alias surname 'Karnstein' that Hanna, Wilhelm and Frank use while in hiding, is the real name of the vampire Carmilla in J. Sheridan Le Fanu's novella of the same name. In the story, Carmillia is revealed to really be called Countess Mircalla Karnstein.
Frank's statement of "Danke fur das gift", translated as 'thank you for the venom', is a homage to a My Chemical Romance song of the same name.
Hanna states that vampirism's origin can be traced back to the rabies virus. Alongside photophobia and other forms of light sensitivity, rabies was a major inspiration for the transmission of vampirism in the series. The two conditions share many similarities, such as the incubation period following a bite, and movement along the peripheral nerves, before a heightened stage of symptoms is reached - known in the series as coming of age.
Mina is named after Mina Harker from Bram Stoker's Dracula.
The book concealing Die Gift's safe in Hanna's house is The Phantom of the Opera by Gaston Leroux. This book and its subsequent musical adaptation feature throughout the series in various forms.
Although Doppelgangers are not traditionally associated with vampires, the Blutsauger and Aufhocker are both found in German vampire folklore. Their names literally mean 'bloodsucker' and 'to jump upon', respectively. In the case of the Aufhocker, this name relates to their practise of jumping onto a person's back before tearing out their throat.
The Alice Cooper song playing through Frank's headphones in Zurich is hinted to be Poison.
David Bernstein's experiments on vampires coincided with the late period of the Scientific Revolution in Europe, when the old superstitions were being transformed by advancements in mathematics, biology, and chemistry. It was not uncommon during this time for dissections and vivisections to be performed on both living and dead subjects, often with no anaesthetic. As Hanna states, the procedures were brutal and unethical, but paved the way for modern science and medicine.
Donaueschingen, Hanna's hometown, is named as such because it sits close to the source of the Danube. This river features in all three Tragic Silence books.
The vampire which is stated to have attacked David Bernstein was James Hayes from Sepia and Silver. James was also responsible for slashing the Doktor's cheek, giving him his characteristic scar.
Hanna instils in Frank not just her life's philosophy, but also inspires his choice of vehicle. She flippantly mentions to him in the novel that she would like to own an old Volkswagen Beetle - several years later in Tragic Silence, this is the car that Frank drives.
The first papers which would later form Die Gift were written in 1756. This date is also the 4-digit code used to open the safe in Hanna's house.
During the final confrontation, Frank leaps between Hanna and Mina with his wings spread. This is exactly the same way he attempts to protect Bianka from her turner in Tragic Silence, ten years later.