Sugarplum

"How DARE you speak to your Queen that way!!"

- Sugarplum revealing her true tyrannical nature as she starts seizing power over the Realms after betraying Clara.

The Sugar Plum Fairy (also known as Sugarplum) is the main antagonist of the 2018 Disney film The Nutcracker and the Four Realms. She is the manipulative and arrogant ruler of the Land of Sweets who plotted to take over all Four Realms with a massive army of Tin Soldiers at her command.

She was portrayed by Keira Knightley, who also played Domino Harvey in Domino.

Personality
As her name suggests, Sugarplum is presumed to be sweet and innocent, even showing concern over the safety of the Four Realms. However, this is nothing more than a facade to hide her true personality: that of a vindictive, ruthless, bitter and manipulative person who desires power in the Four Realms above all else, even with no compassion for anyone else. She is also highly charismatic and dishonest, as she successfully managed to manipulate Clara and the others into falsely believing that Mother Ginger was the evil tyrant who desired to conquer the Four Realms, despite the fact that Sugarplum herself is the real tyrant.

However, this sinister nature is only due to Marie's departure from the Four Realms, which left Sugarplum very embittered as she considered Marie to be a mother figure. This may imply that Sugarplum is somewhat insecure in nature as she felt hurt over Marie's supposed abandonment, despite the fact that Marie entrusted her and the other regents to take full control of their realms. In spite of this, Sugarplum took Marie's departure too deep in heart and decided that the only way to rectify it was to recreate the Four Realms in her own image, something no ruler is ever meant to do. She was even willing to imprison Clara and the other regents out of spite against Marie.

Beginnings
The Sugar Plum Fairy started off as a lifeless porcelain doll owned by Marie Stahlbaum when she was a child, but was later brought to life after Marie created the Four Realms as its first Queen. Sugarplum was assigned by Marie to rule over the Land of Sweets while three others were assigned to rule the remaining realms: Mother Ginger was given control of the Land of Amusements, Hawthorne was given the Land of Flowers, and Shivers was given the Land of Snowflakes.

However, as the years went by, Marie decided to leave the Four Realms for her family, so she left the four regents in complete charge of the Four Realms. Though Ginger, Hawthrone and Shivers accepted this new change in leadership and took control of their realms as agreed, Sugarplum was the only one who disapproved this as she felt betrayed and abandoned by Marie. She then decided that it was time to take over the Four Realms as its new Queen and rebuild them in her own image.

Sugarplum soon learned that Marie created a machine capable of converting toys into living objects (presumably the same one that brought her to life), and plotted to use the machine to create and bring life to an army of Tin Soldiers to accomplish her goal. However, Ginger learned of Sugarplum's plot and tried to stop her, but Sugarplum figured out so she framed her for trying to incite the plot to make sure she doesn't get in the way for the moment, resulting Ginger's banishment within her own realm and a war against the other three realms. Despite the setback, Sugarplum is distraught to learn that a certain key that can activate the machine is lost within the Realms.

Meeting Clara
On Christmas Eve, an ill Marie gets her husband to give their children Christmas presents as her dying wish. Her youngest daughter Clara receives a handcrafted egg-shaped box, and is told by her godfather Drosselmeyer that Marie created it for her. After getting into an argument with her father at the ballroom, Clara finds a string signifying her gift, which leads her into the Four Realms. There, Clara spots the key hanging on a tree, but a mouse steals it for Ginger, much to her dismay.

Clara approaches Captain Philip Hoffman, who takes her over to see Sugarplum, Hawthorne and Shivers, who are all delighted to see the daughter of their former queen. Sugarplum explains to Clara that her mother Marie created the Four Realms and that they are at war with Ginger. Sugarplum also explains the machine that can convert toys into living objects and that she and the other regents want to use it to defend their realms against Ginger and her forces. Sugarplum then sends over Hoffman and several soldiers to aid Clara in confronting Ginger and successfully stealing back the key, but Clara is annoyed to find out that the key can also unlock the egg, which turns out to be a music box.

True Colors
With the key finally in her possession, Sugarplum reveals her true colors by activating the machine and using it to bring the Tin Soldiers to life, admitting that she felt resentful towards Marie for leaving the Realms and that she intends to use her army to take over the Realms as its new Queen. She also informs that the machine can also revert any person living in the Realm back into a toy and that she plans to use it on those who would defy her new reign. Seeing that she got what she wanted, Sugarplum imprisons Clara, Hoffman and the other regents before heading out to initiate her invasion on the Realms.

However, Clara and the others escape while Hoffman convinces Ginger and her minions to help them foil Sugarplum's plot. As Sugarplum directs her Tin Soldier army to invade the Land of Amusements, Hoffman and Ginger's minions fight against several of the Tin Soldiers. In the meantime, Clara successfully enters the machine's room and shuts it down, causing the palace's water wheels to cease rotating and catching Sugarplum's attention.

Death
When an arriving Mother Ginger fights off several Tin Soldiers to buy Clara more time, an angry Sugarplum summons more Tin Soldiers to trap both of them. Ginger and Clara tried to reason with Sugarplum by admitting that they understood how she felt about Marie's departure, but Sugarplum refused their pleas before attempting to turn Ginger into a toy with the machine. However, Clara revealed that she has already reprogrammed the machine into zapping Sugarplum, who is turned back into a lifeless porcelain doll as punishment for her crimes. With Sugarplum's magic undone, all the Tin Soldiers became lifeless as they fell down in defeat.

With Sugarplum and the Tin Soldiers defeated, the Four Realms are finally at peace, and Clara is returned back to her family, where she reconciles with her father.

Trivia

 * The Sugar Plum Fairy started off as a minor but pivotal character in the original story and play while the Mouse King takes on the role as the villain. However, in this film, she is given a much more sinister role as the villain while the Mouse King is portrayed as a loyal servant to Ginger.
 * At first, Ginger was presumed to be the main antagonist, but Sugarplum is the real antagonist as she had bigger plans than anyone else, even framing Ginger for her plot.