Professor de Montfaucon is a character mentioned mainly in The Room Two. He is most noteworthy for apparently inhabiting The Laboratory stage of that game. Montfaucon was one of the many minds interested in the study of the Null and its applications.
Montfaucon focused on how the Null might be used to restore life to dead organisms. Several notecards placed throughout The Laboratory reveal the stages of his experiments, beginning on minor specimens such as rats and beetles, and eventually escalating to human subjects. The first human subject is an arm, given the name “E.H.” in his notes, which can be seen when the player views the film canister as part of the puzzle. The arm is also found suspended in fluid on a lab table in the PC version of the game.
His final test subject is revealed to be the heart of his sister, Lucy. Early in the level, the player finds a letter stored within a drawer, written by a Dr. Beckett of Kirkton Sanatorium, where Lucy was once a patient. Beckett begs Montfaucon to return Lucy to the Sanatorium, stating, “your sister’s condition is not aided by her continued confinement to your estate”. Evidently, this plea was ignored, as a later notecard confirms that a test subject “L” was the last of Montfaucon’s experiments. The final puzzle of the level reveals a human heart, belonging to L, which the player must restore to a semblance of life in order to power a Doorway Machine.
The ending card received upon completing the game contains a quote from Montfaucon, written or spoken in 1903. He speculates that he is not the only one in possession of a Null sample, and that these numerous samples are all coordinated in some way.
A letter in The Room Two - The Crypt credits Montfaucon as often saying "Needs must as the devil drives", which seems to be the foundation of his character. Professor de Montfaucon will do anything it takes to accomplish his goals. Evidently, he has no qualms with deviating from the law, as he is implied to have engaged the services of Mr. Rigby, a grave robber, to obtain some of his test subjects. Despite his unscrupulous morals, he does appear to be genuinely concerned with saving his sister's life, going so far as to take her treatment into his own hands rather than leaving her in the care of the sanatorium. Dr. Beckett, Lucy's doctor from the sanatorium, believes his motivations to be altruistic, and Montfaucon's final note to Lucy begging for her forgiveness reveals his legitimate grief over being unable to restore her to life.
Montfaucon encourages the mysterious writer of the letter in The Room Two - The Crypt to trust Mr. Rigby, a grave robber tasked with retrieving a Null artifact for his employer. Montfaucon vouches for Rigby's character, having apparently hired him for his own purposes in the past. From the nature of Montfaucon's experiments, it is likely Rigby provided corpses for the Professor to study.
A.S. apparently knows of Montfaucon’s experiments, but the nature of their relationship, if any, is unknown. A.S. admits that Montfaucon’s work is more advanced than his, but also claims that Montfaucon never found the secret of the doors: the importance of the soul. There is some reference to a bargain that was made between the two - with AS trading his soul for Lucy's so that Lucy's soul might be used by the protagonist to escape the Null dimension. Presumably, AS's soul was used in Montfaucon's experiments.
Montfaucon's motivations for experimenting on the body of his sister are open to interpretation. It may be that Montfaucon was driven solely by his desire for knowledge, therefore viewing Lucy as no more than a test subject. However, considering that Lucy was confined to Kirkton Sanitorium, an institution for the treatment of tuberculosis patients, it is more likely that Montfaucon believed his experiments could save his sister's life. By this interpretation, the handwritten note on Lucy's subject card - "Dear Lucy. Forgive me. I was too late." - could be attributed to him. This is further supported by the handwriting on the film canister found during the puzzle being a match for the handwriting on the notecard. Montfaucon was willing to go to extreme lengths in order to save his sister's life, but unfortunately failed to do more than cause her heart to beat posthumously.
There is some evidence to suggest that Professor de Montfaucon and Hugo Waldegrave were, at one time, scientific colleagues. The beetle collection in Montfaucon's lab resembles a similar collection found in the Curiosity Room of Waldegrave Manor, and is labeled in what may be Waldegrave's handwriting. Waldegrave could also be the acquaintance that Montfaucon recommended Rigby's services to, judging by Waldegrave's wealth and his interest in obtaining rare artifacts.