Something I intended to mention in connection with the novel was the fact that Hambly introduces Wotan (Odin) in the manifestation of Renfield's madness, especially in connection to Wagner's operatic version.
Odin, Odhinn, Woden, Wotan - Ruler of the Æsir, God of the runes, inspiration, shamanism, magic and war. God of the hanged and the Wild Hunt; God of storm, rain and harvest. A shape-shifter, he makes men mad or possessed with a blind raging fury. He produces the battle panic called "battle-fetter". Three different frenzies or madness are his gifts to humankind: the warrior in battle, the seer in trance, and the poet in creativity. Subtle, wily, mysterious and dangerous, he often ignores pacts made in honor with humans. Attended by his two ravens, two wolves and the Valkyries. Feared by ordinary people and worshiped only by princes, poets, the berzerkers, and sorcerers. Unpredictable when invoked... (from Norse Gods, Goddesses, Giants, Dwarves and Wights)
There are certain similarities that make Hambly's choice of Wotan in connection with Renfield's first obsession a good one as Renfield functions as a harbinger of Dracula, and the Wotan myth presages the Dracula myth. Another interesting aspect is the subtle connection Hambly makes with Germany's preoccupation with Wagner, especially The Ring cycle, (and Wagner's Wotan is the Wotan to whom Renfield refers) to the minor character Gelhorn who has an obsession with the superiority of the German race and a makes an almost throw-away prediction to future historical events.