It’s pretty easy to see that Sybill Trelawney, the eccentric and over-dramatic professor of Divination was not a great teacher. All the other teachers seem to find her frustrating at best, and she hides away in her tower to keep away from them. Headmaster Albus Dumbledore mostly gave her the position to protect her after she made the prediction that led Voldemort to kill Harry Potter’s parents.
Trelawney does have some moments when her predictions come true. But she mostly capitalizes on the power of suggestion, vague statements, and sophistry. Here are ten times those tendencies could have gotten her fired.
No one would ever call Trelawney calm. She is given to drama and makes predictions of misfortune as easily as other people breathe. In Order of the Phoenix, when she is being harassed by Dolores Umbridge, Trelawney reacts poorly to the evaluation. Nearly every teacher hates Umbridge's interference, but Trelawney seems to be the only one that takes it out on her students.
In Prisoner of Azkaban, we’re introduced to the Grim, a giant spectral dog that foretells death. Almost every child who grew up in the Wizarding World seems to believe in it.
When Trelawney sees a dog in Harry’s teacup, she claims it is the Grim. Naturally, this is another prediction of Harry’s tragic and untimely death. It’s arguable, however, that the dog in Harry’s cup is a prediction of Sirius Black’s entrance to his life. Sirius’ Animagus form is a giant black dog, and he uses that form to escape Azkaban and get onto Hogwarts grounds. Trelawney is Seeing the future but she doesn’t understand it at all.
In Goblet of Fire, Trelawney seems to take special joy in predicting something painful for Harry in every class. Professor McGonagall and Dumbledore both assure him that this is something Trelawney enjoys doing with many students. But given Harry’s reputation in the Wizarding World, it’s easy for her to capitalize on him to impress everyone.
Of course, keeping her threats vague means that she’s always going be technically right. Telling Harry that there are “difficult times ahead” could mean anything from struggling through school assignments to fighting Voldemort. Of course, he does both in his fourth year.
Trelawney often uses her “gifts” to achieve ends. She particularly uses Neville’s anxiety against him, as she does in his very first class. Seeming Neville’s clumsiness, she “predicts” that he’ll break a cup, which of course became a self-fulfilling prophecy.
She trades on that again during finals. Naturally, her goal is that the students don’t cheat by telling each other about the final. But playing on Neville’s clumsy anxiety is a cruel way to do it.
In her profile of Trelawney, JK Rowling wrote that Trelawney loves impressing gullible students with predictions of doom and disaster. As with all false predictions, these sort of “predictions” work best when they’re kept vague. While sometimes she trades on the power of suggestion, making a vague threat with a deadline plants a seed of doubt.
It’s only natural that Lavender would do the work for her. Despite the fact that her rabbit doesn’t actually die on the sixteenth, Lavender considers the prediction fulfilled. And that’s all it takes for her to cement Lavender’s faith.
Once again, Trelawney capitalizes on Neville’s nervousness for one of her “predictions.” As an adult who had survived the first Wizarding War against Voldemort, Trelawney would know who Neville Longbottom’s parents were. Both were tortured until they were insane. After that, Neville grew up with his grandmother, his only remaining family. Trelawney asks after his grandmother, knowing Neville would fear desperately losing her as well.
For the most part, Professor Trelawney keeps to herself. She rarely descends to join the rest of the school because she claims it clouds her Inner Eye. It could also be because she realizes that the other teachers are more competent than she is and don’t take her seriously.
As far as we know, however, none of the other teachers insult each other to the students. Trelawney and Firenze, a centaur Dumbledore hires after Umbridge fires Trelawney, have a rivalry that leads to them insulting one another in front of students. He calls her work “human nonsense,” and Trelawney reduces him to a horse in front of a student.
Everyone has work disputes. No job is perfect. But shouting at your boss rarely goes well. Trelawney, however, in her fury about Firenze remaining at the castle in Half-Blood Prince, seems to pick fights with Dumbledore numerous times. She wishes for Firenze to be fired, and doesn’t seem to understand (or maybe simply doesn’t care) that to fire him would be to condemn him to death.
From what she said to Luna, this doesn’t seem like the only time Trelawney has had this fight. No wonder Dumbledore, who normally remains calm, is “exasperated” by her.
According to McGonagall, Trelawney predicts a student’s death every year and it has never come to pass. But that doesn’t stop her from doing it anyway. Given that she is always latching onto students who are already nervous or believers (Neville, Lavender, Parvati), this is a disturbing habit of hers.
Surely there’s some rule that even if a Seer does See death for a student, she should protect that child from it? Someone call in Dumbledore on this one, it’s a really cruel thing for her to keep doing.
Multiple times when Harry meets her, Trelawney smells of sherry. When she speaks to Luna in Half-Blood Prince, Trelawney responds with “an angry, drunken titter.” Rowling writes that Trelawney “developed an over-reliance on alcohol” due to her perceived ill-treatment.
Alcoholism is an addiction and should be treated as an illness, not a character flaw. However, Trelawney seems to often be drunk in front of students. She lives in Hogwarts Castle and should be upholding decorum for the students. As a professor, she is supposed to be a leader for the students. Drunk at work is not a great example.