Hermione Granger is often remembered as a strong, independent, and intelligent young woman. Usually seen with a book, Hermione was the brains of the Golden Trio. While she did not hit it off with Harry and Ron immediately, they became nearly inseparable after the troll incident. Afterward and throughout the rest of the Harry Potter series, Hermione is acknowledged as Harry's most loyal friend, even edging out Ron on certain occasions.
Nothing got in her overall motivation to keep Harry safe and help him defeat Voldemort and his Deatheaters. As academically brilliant as Hermione is, not all of her choices align with the title, "Brightest Witch of Her Age."
10 ANNOYED BY PEOPLE'S LOVE OF DIVINATION
In a world of magic, it gives the illusion that anything is possible. For Hermione, it gives the illusion that nearly anything is possible. She is more than willing to accept spells, potions, magical creatures, and other such attributes of the world, but divination is a step too far.
Divination does not follow a direct formula or textbook which is problematic for Hermione. She does not understand the craft of the class or how it is anything other than guesswork. She can not leave it at her displeasure though, she must constantly reinforce her beliefs, looking down on those who find the subject interesting.
9 CONFUNDING CORMAC
Hermione's romantic feelings for Ron only grew throughout the series, as did her desire to see him succeed. Ron's sixth year Quidditch tryout for Keeper makes him a nervous wreck and he is unable to play to his full ability. During his turn, his nerves catch up to him while Cormac does spectacularly.
Wanting Ron to take the slot on the team, Hermione uses the confundus charm on Cormac, making him miss a shot as Ron's confidence grows. Although she had only wanted Ron to continue being on the team the act was still cheating.
Given the situation, if Hermione is going to go up against an authority figure, then likely she has a justified reason. However, in Harry Potter and the Chamber of Secrets, she creates a plan to steal ingredients to make polyjuice potion. While her actions were meant to find out the identity of the Heir of Slytherin, there was no guarantee that she would successful brew the potion.
The potion only worked for Ron and Harry. Hermione's had included cat hair rather than human, landing her in the hospital wing. Had something gone wrong she could have left any one of them seriously hurt.
7 HALF-BLOOD PRINCE'S BOOK
Always the best in class, Hermione is surprised that Harry is surpassing her in Potions, one of his worst subjects. While she is usually supportive of her friends' academic growth, she is not thrilled with the source of Harry's improvement. Harry's old textbook has notes in the margins contradicting those in everyone else's book.
It also holds spells neither of them has ever heard of with no explanation of what they do. Hermione actively tells him to get rid of the book and allows it to grow into a small feud between them.
6 THE FIREBOLT
In Harry Potter and the Prisoner of Azkaban Harry receives a Firebolt as a Christmas present. However, the gift has no name attached to it. Excited about the new broom, Harry and Ron ignore Hermione's first instinct, the broom was sent by Sirius Black. Sirius, considered to be a mass murderer on the run to kill Harry, is a likely suspect, yet Hermione is the only one concerned at the possibility.
Worried the gift was intended to harm Harry, Hermione goes behind his back to Professor McGonagall. Luckily, the broom is not cursed, and Sirius Black later proves himself to be innocent.
5 BODYBINDS NEVILLE
Harry, Hermione, and Ron made it a mission to retrieve the Sorcerer's Stone before Snape. However, they also wanted to keep it a secret to avoid getting into trouble or getting anyone else hurt or involved. Neville had beaten them to it, already in the common room when the trio are about to leave.
He had been waiting for them, prepared to stop them and goes as far as to say he will fight them to keep them from leaving. Even though she apologizes, Hermione does not explain her actions when she body binds Neville, leaving him on the floor. He is stuck there until Professor McGonagall finds him later.
4 ATTITUDE TOWARD LUNA
Growing up in the muggle world, and later in Hogwarts, Hermione was often bullied for her intelligence and attention to learning and homework instead of social activities. For someone who had difficulty making friends until she met Harry and Ron, Hermione's treatment of Luna Lovegood when they first interact is quite hypocritical.
Luna is drastically different from Hermione, believing in creatures others can not see rather than Hermione's viewpoint of believing what is found in textbooks. Hermione's lack of patience for Luna's view of magic and life goes against everything she would have believed in before making her circle of friends.
3 ATTACKED RON WITH BIRDS
Ron's popularity skyrocketed in the aftermath of his fantastic Quidditch performance. He is the life of the party in the Gryffindor Common Room and everyone is excited to congratulate him. Of everyone who celebrates, among them is Lavender Brown, another student in their year. Thrilled at receiving recognition by his peers and a kiss from Lavender, it is a successful party for Ron, but not as much for Hermione.
Heartbroken that her impression that she and Ron were moving into more romantic territory was shown to be wrong after seeing him and Lavender together, Hermione leaves the party to have some time to herself. Harry quickly joins her, with Ron and Lavender following quickly behind. Hermione, upset at seeing them, sends charmed birds to attack Ron.
2 LEFT HARRY ISOLATED
Hermione is arguably Harry's most loyal friend. While she stands by his side for every large, important moment, she does not come through in the aftermath of Voldemort's resurrection. While Hermione goes home to her parents and Ron to his family, Harry is left alone at the Dursley's with no news about what is happening in the wizarding world.
He is forced to watch for scraps on the local news for any oddities. When they reunite at Grimmauld Place, Hermione is quick to answer all questions, but that does not erase three months of silence.
In Harry Potter and The Goblet of Fire, Hermione witnesses Barty Crouch treat his house-elf, Winky, awfully. In response to this as well as knowing about Dobby's history with the Malfoy family, Hermione invents S.P.E.W, the Society for the Promotion of Elfish Welfare. It was created to protect house-elf rights and allow them the ability to have days off, get paid, or be allowed to be free.
However, while she believes her actions are helpful to house-elves, who are treated as slaves, this is not the case. Many tell Hermione that house-elves enjoy working and that most do not wish to be freed. Hermione powers on though, attempting to rally many to join the cause including Harry, Ron, and Neville. While the intent is to help, Hermione had not spoken to the house-elves directly about what they wanted for themselves in her determination to free them from what she believed was wrong.