Lennie wanted to pet the mouse as he walked as he loves to pet soft things.
Once his aunt Clara used to give him mice to pet but she stopped giving them to him because he was petting them too hard and killing them.
Slim has the Puppy that Lennie Wants, that George Promised him to replace the dead mouse.
A dead mouse
He wants to pet it with his thumb
Lennie takes a dead mouse out of his pocket, which causes George to yell at him because he knows that Lennie's habit of petting soft things often leads to trouble. George doesn't want Lennie to get in trouble again.
Lennie kept a dead mouse in his pocket because he enjoyed petting soft things and found comfort in touching the mouse's fur.
Lennie brings back a dead mouse that George takes away from him. Lennie's fascination with petting soft things causes George to remove the dead mouse as it is not suitable for petting.
A dead mouse
The main two main reasons why George didn't want Lennie to have a mouse are that he kills the mouse without knowing/realizing his own strength when the mice bite him, and Lennie bothers George by bringing that same mouse but Lennie doesn't know that bothers him. Lennie acts like a child mental.
Lennie keeps a dead mouse in his pocket, which he likes to pet and take care of. Later, he goes searching for the dead mouse after realizing he has lost it.
Lennie has a dead mouse in his pocket, he has it so he could stroke its fur while they walk around.
The main two main reasons why George didn't want Lennie to have a mouse are that he kills the mouse without knowing/realizing his own strength when the mice bite him, and Lennie bothers George by bringing that same mouse but Lennie doesn't know that bothers him. Lennie acts like a child mental.
Lennie felt disappointed and confused when George threw the dead mouse that he had been petting, as he didn't understand why George would do that. He was also hurt by George's actions as he viewed the mouse as a source of comfort and companionship.