Hector Mascari is a functional human who has been hybridized with a rat.

However, Hector is not a functional human hybrid who can be released out into the general population.

In appearance, Hector touts bristly but long and stiff mustache hairs (very sparse), light down over his body, and an exceptionally pointed face that appears like a snout from certain angles. He is very outgoing and friendly and likes everyone he meets, almost without exception. He is quick to respond to outside changes, the quality the rat was selected for. The rat qualities that didn't hybridize so well are that Hector sniffs frequently, doesn’t like his mustache (whiskers) touched, and craves cheese.

Hector bathes constantly, is a constant hand washer, and keeps his clothes immaculate (even if he has to offend people to do so). Hector tends to snatch pretties and abscond with them. His stash of "pretties" grows and grows, and it seems there's nothing he can do about it.

Hector really wants to join the research team. He is smart enough. The challenge is staying focused to finish the training.

We first meet Hector in Book 2 of The Human-Hybrid Project, Inside the Darkness.