After talking to the Other Father, who seemed to have become rather different and gloomy, Coraline saw the Other Mother in the living room, expecting her. The Other Mother forced Coraline to accept her love to which Coraline refused again, and finally, the Other Mother's appearance began to change and became more like her real one.
While the Other Mother appears good at cooking, she is never seen eating. When both Coraline and the Other Father have a full plate and eat from it, the Other Mother never puts anything on her own plate. She was only seen eating a coco beetle and attempting to eat Caroline like she did to the ghost children, this is because of her true form of a spider in the movie. (Above Art by Stephen Knox)
One last thing the other mother wants to eat Coraline because she is crazy and not normal.
She kidnaps and eats children who move into the pink palace (which is why Wybie's grandmother won't rent to people with kids).
At first, the Other Mother is shown to be rather sweet and considerate, maybe even selfish or narcissistic in a way, because she seems pampered and rather fond of herself, while greeting Coraline with a loving and caring persona, everyone was clueless as to who she really was. Over time, however, as Coraline rejects sewing buttons into her eyes, her personality slowly begins to erode and warp, showing a more sinister light (dark more like) in her behaviour. She becomes less patient with her, becoming less sweet and more obsessive in her goal to eat Coraline and trap her spirit like she did to the ghost children. According to Shommp, the Other Mother does love Coraline, but does so possessively. This has been showed throughout the text, when Coraline admits the Other Mother does love her. Though this is similar to a pet with obsession. This has only been explained in the novel.
It is implied that she is very sadistic and cruel to her creations, forcing the Other Father to manage the praying mantis tractor machine to fight off Coraline's search for the eyes, as well as stitching Other Wybie's mouth into a crooked smile as punishment for frowning when saying "goodbye" to Coraline.
A constant in her personality (aside from her obsession with Coraline) is her love of games, allowing Coraline the risk of finding the ghost-eyes and her parents for the sake of the game. She seems to tap her fingers on a surface whenever it is brought up, implying excitement from the idea.
However, it is known that she does not play by the rules and prefers to resort to cheating. That or, at least, try to noscope her victim's efforts.
She also seems to hate cats - calling them "vermin" - though this could be because of how easily they can benefit from her world.
In the book, it was implied that the Beldam had been a sadist ever since childhood, shown when she swore on her mother's grave.
Powers and Abilities
The full extent of her abilities have yet to be revealed, but it is clear she has near omnipotent (and mild omniscient) power over the Other World and all of its inhabitants. She has the power to create life, ranging from people to animals and fully animate plant-life. How they behave seem to depend, as the animals and plants seem to be under her full control, while certain human-creations like the Other Father and Other Wybie have some kind of free will. It is implied that she hand-made the Other World in the same manner as an artist and a sewer would, every living thing in the Other World possessing button-eyes and other Wybie's hand being made of sawdust beneath his glove.
The Beldam is also apparently able to kidnap and temporarily store the parents of her victims, as Coraline's parents were held captive by the Beldam in the The Snow Globe, and emerged without any memory of the experience.
She has the power to shape-shift, first taking the form of her victim's mother (albeit more lively and inviting) and slowly transitions into her true form overtime, slowly deteriorating like the rest of her creations. It is shown that her buttons operate as fully-functioning eyes, becoming blinded and relying on the vibrations of her web and her sense of hearing to navigate when the cat clawed them off.
She is also able to possess the souls of those she has claimed, the ghosts of her previous victims trapped in the Other World unable to pass on.
Despite her immense powers, her abilities clearly has their limits. Apart from her creations acting upon their own free-will should they try it - nearly compromising her plans on more than one occasion - she is also unable to replicate the key to the doorway in and out of the Other World, having become trapped when Coraline locked the door forever.