Dr. Williams is the name of Max's biology teacher while the Flock is at school in Nevermore. However, he is not seen in any other books.
When Max walks into the classroom, he tells her that he's glad she could join them. Once everyone is seated, Dr. Williams passes out packets of paper. He tells everyone that they'll be doing their first hands-on lab assignment…and, unfortunately for Max, the packet says Chicken Dissection Lab. A bit into the assignment, Dr. Williams asks Max how it's going; it is during this that she first makes the assumption that he was a whitecoat. He tells her that "the boys seem fine" when she calls for Iggy and Dylan (who all start feigning sickness), but Max ignores him. As the bird kids are going for the door, he tells Max, "Oh, no, you don't, Maximum." Max, Iggy, and Dylan brace themselves for a fight, but Dr. Williams does nothing dangerous—he just goes to his desk and writes them some hall passes.
After they'd fled, Dylan had realized that he'd left behind one of his textbooks, so he'd gone back to the lab to get it. However, before he can leave again, Dr. Williams tells him that Max's life is in danger. He says that he can keep her safe, if he cooperates with him. Dr. Williams tells Dylan that he has important information from Dr. Hans Gunther-Hagen, shocking the bird kid. Even after saying that it was impossible, Dylan was told that his creator was alive, and that he's been seen...and he also has a special but secret mission for the bird kid. The mission involves Fang; according to Dr. Williams, Fang is a far bigger threat that anyone realized, because his DNA is, in a way, dangerous. Dylan is highly skeptical at first, but Dr. Williams tells him about tests, experiments, and discoveries that supported what he'd said. However, even after learning the information, Dylan still doesn't know whether or not he believes it. He is told that he must capture Fang and bring him to the whitecoats. Dylan tries to refuse, but Dr. Williams tells him that they'd have to kill Max if he didn't accept.
Later, it is revealed that Fang's DNA holds science's key to immortality, and that this was the threat Dr. Williams had been referring to.