Jasper's appearance, like all lamia, is notably handsome. He is described as having "dark hair" and "an aura of power and purpose. But not of warmth". Being a wealthy psychologist, Jasper is shown wearing expensive and well-tailored suits.
Jasper appears to be well-trained in the tenants and teachings of the Night World, viewed as a calm, confident man with a controlled aspect to both his outward demeanor and his emotions. However, like his wife Madder, he appears to be lacking in familial affection, seeming clinical and detached from his own son. Despite knowing of James's friendship with Poppy North, Jasper feels no attachment to her either. In fact, when told by James of the girl's cancer, the elder Rasmussen was genuinely surprised at the fact that James came to tell him this rather than surprised at the knowledge that Poppy was sick. As such, it can be inferred that Jasper tolerates human beings but sees them as nothing more than something to feed on.
Both he and his wife were responsible for orchestrating the death of James's beloved nanny, Miss Emma, whom they felt James was becoming too "attached" to.
Dr. Rasmussen is mentioned and met early in the book; unwilling to let Poppy die of her cancer, James seeks out his father for advice on how to help the teenager. However, although his father is outwardly welcoming to James, Jasper utterly fails to understand his son's concerns. He even goes so far as to suspect James of being "too attached" to Poppy, the same way James had been affectionate towards Miss Emma. Worse, upon James's pleas to help Poppy, his father misunderstands James's emotion for pity, and believes his son wants to conduct a mercy-killing on Poppy to spare her suffering. Sickened at the idea, James departs, curtly answering his father's mild questions about school and his apartment before leaving. A few days later, Madder requests to speak with her son, as Jasper had mentioned their prior meeting to her.
- In nature, jasper is a red or green form of chalcedony, and was a commonly used gemstone in ancient times. Wearing jasper was said to promote protection, health and beauty, as well as suppress unwanted desires (similar to the lamia vampire's own emotional suppression). In some traditions, it is the birthstone for the month of March.
- ↑ As seen on the Redfern and Harman Family Tree