Inhabiting a lab in the lower level of Navarro, Doctor Schreber is a thoroughly amoral man. Although his primary task is the analysis and experimentation upon an intelligent deathclaw captured by an Enclave patrol, he also dedicates considerable effort to extracurricular experimentation. This has been a source of friction between himself and the base's commanding officer.
In the interests of morale, the base CO had Schreber's lab soundproofed, so that the "patients" the doctor was working on would not disturb the rest of the base with their screaming. Although Schreber had no way of knowing, he inadvertently set the stage for a very dangerous encounter; nobody would be able to hear a shout for help, either.
Schreber had a literal "pet" project, a cyberdog called "K-9." K-9 disapproved of Schreber's actions, and friction between the two built until, unable to accept Schreber's behavior any longer, K-9 bit the doctor. In retaliation, Schreber disabled K-9's legs, forcing him to stand, still as a statue, and watch every experiment.
Since his room is soundproof, while sneaking through Navarro, the Chosen One can kill him with only K-9 noticing. Other than that, he is a flavor character only (though his death is required to acquire K-9 as your companion).