The only member of the human collaborators known as The Watched to be identified by name (as of this writing), Calvin is first seen in Behind Enemy Lines.
Calvin's history is unclear at this time; it is also unclear if 'Calvin' is his first or last name. It is known that he was a minor official in the county he lived in before he was abducted, and saw a chance to save himself by becoming one of the collaborators that assist the Slaver Mantoids (how this happened is also unknown). Calvin is a petty, arrogant man that is nonetheless very effective in his duties, rewarding slaves for exemplary work or for acting in a manner that pleases him. He is also known as a sexual deviant, who enjoys having women submit to him sexually (either personally, or by having them engage in lesbian acts so that he can watch or just know that he had them perform as such), and that he is a very deep sleeper after frequent, intense sexual escapades. He is also very highly trusted by the Slaver Mantoids (for what reason is unknown), as he was not only allowed to learn how to understand and write in the alien's language, but to keep manuals pertaining to the language in his personal quarters (in and of itself a sign of the level of their trust).
Calvin has developed a personal interest in Anita Isakson, and while he has compelled her to submit to him sexually at a moment's whim (among other things) since noticing her several weeks after her arrival, he has provided her with a number of luxuries that set her life apart from the average slave. These include work details in 'The Gardens' (the massive agricultural areas aboard The Habitat), the chance to study and learn the Mantoids' written language, and not taking any sort of actions against Franklin Davers because Anita considers him a friend. Anita, however, hates him with a passion, but submits because she wishes to live, and also because she understands the value of her position as one of his preferred lovers due to the valuable information she has access to.