Black is a young man with the aspiration to become the Champion of the Unova Pokémon League. This dream has been his driving force since childhood, precisely nine years ago. However, these dreams dominate his thoughts so much that he can't focus on anything else, leading to mental exhaustion and fainting spells. With the help of his Munna, Black can consume his dreams, which he describes as turning his mind from "blank white" to "solid black." This process allows him to think more clearly, become smarter, and enhance his perception. Interestingly, when this happens, he reportedly sees the world in hexagons. Due to his preoccupation with his dreams, Black often acts without considering the consequences of his actions or their impact on others. As the story progresses, Black gradually starts to consider the feelings of others and manages to think about other things for brief moments.
Several characters describe Black as "hot-blooded" because of his loud personality and tendency to act independently. He doesn't understand show business like White does, and many aspects of it surprise him, such as Gigi and Tep staying in a hotel room while he and White have to camp out. Black is very familiar with libraries, having visited them frequently during his childhood, enabling him to solve Lenora's Gym puzzle quickly and set a new record. His penchant for dreaming also causes him to miss important events around him, such as forgetting his promise with friends Cheren and Bianca after receiving the package containing the Pokémon and Pokédexes they were supposed to receive.
After defeating N and Ghetsis, Ghetsis used Colress's Beheeyem to push Black while Reshiram was transforming, causing Black to merge with the light stone.
(Source: Bulbapedia)
