Contessa Maria Sinistre - more commonly known by the members of H.I.V.E. as The Contessa (English: Countess) - is a former H.I.V.E. teacher who had the unique ability to control almost anyone using her voice.
She uses the voice on Otto and Wing when they arrive at H.I.V.E. and starts to ask awkward questions. The Contessa teaches polititical and financial corruption which Laura enjoys for reasons not understood by her friends.
The Contessa had a daughter who died and her granddaughter
is was Lucy, also deceased.
In the first book the Contessa shows the new Alpha stream students around the school. When Wing and Otto begin asking awkward questions she uses the voice on them, preventing them from remembering what they were going to ask, from then on, Otto and Wing tread around her more cautiously.
In The Overlord Protocol, it is revealed that the Contessa was being bribed to work for Cypher. Using her ability of vocal-manipulation, she subdues both Professor Pike and Colonel Fransisco, along with Block and Tackle, using them to both render the H.I.V.E. complex vulnerable to Cypher's planned attack, and to place an explosive charge in the facility's geo-thermal power tap as a contingency plan. She is taken to Number One at the end of the book.
After Nero goes missing she is installed as headmistress of H.I.V.E. to Otto, Wing, Shelby and Laura's dismay. Number One uses her to do a multitude of things at H.I.V.E, which Dr. Nero would never have approved of. She puts in place some new protocols. Later on, she uses one of them to knock out all the students and staff in the school so she can "relocate" Otto, Wing, Shelby and Laura to somewhere, but we never find out where due to the fact that Raven stops her before she can succeed. Towards the end, Number One has her install a mysterious package which we later find out were several canisters of nerve gas, which he intended to kill off the entire Alpha stream with. She seems reluctant to do it, and she seems to regret everything she's done in the book, causing to re-join sides with the other main teachers. When Number One sends the Reapers to HIVE, she puts shroud fuel on the floor of the main hangar, where the shrouds come and go from, and she drops a lighted cigarette onto it, instantly alighting it and killing the Reapers and herself in the process with the quote "This really is a dirty habit. I really must give it up," saving everyone in H.I.V.E. Dr. Nero commemorates a statue to her and H.I.V.E.mind which is a block of marble with a blue laser and the Sinistre family crest carved into it.
The Contessa is old. She has long hair that is always put up, not in a bun or anything like that but she has it slicked up high in the air. She has an addiction to cigarettes, which she describes as a "filthy habit" in the third book.
The Contessa has the unique - and completely natural, as far as anyone can tell - ability to foribly manipulate other people with her voice. Her vocal-manipulation is easily distinguishable from her regular speech in that it takes on a plethora of barely audible, and sinister whispers when she uses it. When she uses The Voice on others, it is described as the mind being a passenger in the subject's body, resistance being completely useless.
There are only two countermeasures to The Voice which are known. The First is simply wearing ear-plugs, as while they do not completely filter out sound, the whispers which seem to be the operating component of the voice are silent to the subject, allowing the subject to effectively free themselves before they are even "captured" by it. The Second countermeasure is simply interacting with the Contessa via telecommunication, as the effects of The Voice do not appear to be able to travel across electronic communication links.