Professor Sinister is the Deviation teacher of Hogwarts. She is a half-Japanese half-vampire and, like Ebony, a goth. This is the reason she is Ebony's favorite teacher. She gained her vampire gene from her mother, but it is not known whether her mother is a Japanese vampire or if her father was a Japanese mortal (probably the latter).
Like other Professors, Sinister appears completely unfit to teach. Her behaviour is consistently crude and offensive. It seems in most classes she 'fucking' dismisses them almost as soon as they begin.She is astonishingly foul-mouthed, makes a habit of calling students profane, insulting names and even calls her favourite student Ebony a cunt to her face. She allows students (only "goffick" ones) to call her similar names., but dislikes "prepz" like Britney whom she treats unfairly, forcing the preps to stay behind and do 'exorcizes'. She is the one who invents the plan to send Ebony back in time, and she arms Ebony with a gun.
Professor Sinister helps Ebony decipher some visions she had. Sinister reveals that Ebony must go back in time to seduce Voldemort into loving her. This way Voldemort knows how to love and will not become evil.
After Ebony's first trip back in time, Trevolry confesses she got addicted to Voldemortserum, which apparently is a very addictive substance. She asks Ebony to find a cure to this addiction. Ebony suggests going to St. Manga's, but Professor Sinister refuses to go. Trevolry also gets sent to Abkhazian by the Mystery of Magic. The reason given for her imprisonment is that she is too gothic. But she returns inexplicably to reveal to Ebony that Britney released Snap, Loopin and Hargrid.
"OK class fucking dismissed every1." Proffesor Trevolry said and she let every1 go. “Except for you Britney.” she pointed at Britney and sum other preps. “Please do exorcize (geddit) 1 on page 3. ”
- "Okay you can go now, see ya cunt." said Proffesor Sinister.
- "Oh hey there bitch." Profesor Trevolry said in an emo voice dirnking some Volxemortserom.
- “Cum on Enoby.” said Proffesor Sinatra. She was wearing a gothic blak leader dress with a corset top and real vampir blood on it and fuking black platinum boots. “I have to tell you the fucking perdition.”
- I smelled happily and went into a dark room. I had changed Profesor Sinister took out some black cards. She started to look into a black crucible ball. She said……………………… “Tara, I see drak times are near.” She said badly. She peered into da balls. “You see, you must go back in time.” She took out a Time-Toner like B’loody Mary had. “When Voldemint was in Hogwarts before he became powerful he gut his hearth borken. Now do you fink he would still become Volxemort if he was in love?” I shook my head. “U must go back in time and sedouce him. It is the only way. If he is still evil then you must kill him. You can come to my room tomorrow and you can do it.”
- "Ebony I was so worried abott u but I know you can't fucking die because you're a vrompire. Snape came back because that girl Britney freed him. I never liked her she was a bad student." Trevolry said reassuredly.
- “OMFS, letz have a groop kutting session!11” said Profesor Trevolry.
- Professor Sinister/Trevolry appears to be an amalgamation (or, as Tara would put it, a pentagram) of Professor Aurora Sinistra and Professor Sybil Trelawney from the original series, but draws more inspiration from the latter. This is apparent as she teaches Deviation, which appears to be based on Divination, the subject Trelawney teaches. Both classes involve the planets of the solar system, which may have led Tara to confusing the two for each other. While Trelawney shows up frequently throughout the books and films, Sinistra does not get any dialogue whatsoever and barely appears, and was only in the background in the film of Philosopher's Stone in a silent role. (In this appearance, Sinistra was a black woman, while Trelawney is Caucasian.)
- Her addiction to " Voldemortserum" was an attempt by Tara to prove that the story dealt with serious issues. It seems like Tara meant to say 'Veritaserum', a potion that forces the drinker to tell only the truth, but there is nothing in canon to suggest this substance is addictive, nor is Trelawney involved with it.
- She appears to be a weeaboo, knowing only Konnichiwa.
- Her name could be based on the Sinister sisters characters from the 2006 movie, Return to Halloweentown.
- It's claimed she and B'loody Mry/Mary get along 'grate'. Not only is this irrelevant as the two characters never significantly interact in the story, it is the complete opposite of canon. Hermione Granger gave up on Divination, Trelawney's class, before the end of her third year (she used her Time Turner, not 'Toner', to go back in time and thus attend more subjects), and did not have a fond impression of her at all.