He was shot by George
Lennie accidentally killed his puppy when it acted like it was going to bite him.
Lennie is always Soft. We can see that many times in the novel.
Lennie needs someone to care for him and tell him the "dream" to keep him going
he does not have a work card in his pocket
George and Lennie are two friends who travel together looking for work during the great depression. Lennie is mentally disabled and George looks after him in a way.