Lennie Small is one of the main characters in John Steinbeck's Of Mice and Men. Contrary to what his name suggests, Lennie is physically very large and strong. He is compared to a bear because of his size and strength. Mentally, he is childlike and has a very limited understanding of the world. For this reason, he is completely reliant on George to guide him, teach him, and keep him safe and out of trouble.
Lennie's extreme physical strength and severely limited awareness are a dangerous combination. Lennie often does not realize his own strength, and he has a love for soft things: this results in him inadvertently killing small animals and, ultimately, Curley's wife.
One of Lennie's most notable characteristics is his loyalty to George. Although he probably would not be able to define loyalty if asked to, Lennie greatly respects George and tries his best not to disappoint or upset him. Despite his best efforts, Lennie's lack of intelligence often causes him to unknowingly engage in behaviors that anger George and put the pair in danger.
Lennie has unwavering enthusiasm about his and George's shared dream of owning their own farm. George is realistic and only partially believes in their dream, but Lennie is filled with childlike wonder and never doubts that their dream will be realized one day.
While he has a central role in the story and its plot, Lennie does not undergo any significant growth or changes throughout the novel. At the end of the book, he remains much the same as when we first met him: a large, strong, mentally incapacitated man with a simplistic view of the world, intense loyalty to George, and a love of soft things.