George expresses his frustration:

“Jus’ wanted to feel that girl’s dress—jus’ wanted to pet it like it was a mouse—Well, how the hell did she know you jus’ wanted to feel her dress? She jerks back and you hold on like it was a mouse. She yells and we got to hide in a irrigation ditch all day with guys lookin’ for us, and we got to sneak out in the dark and get outta the country. All the time somethin’ like that—all the time.”

George is extremely frustrated with Lennie. Lennie is always causing a disturbance of their peace. George is frustrated.

Another reason for George's frustration is the fact that Lennie has a dead mouse in his pocket. Lennie is too strong for his own good. He pets the mouse and kills it. George becomes frustrated with Lennie. He insists that Lennie hand over the dead mouse. Lennie does not want to release the dead mouse. George has to express his frustration in such a manner until Lennie hands over the dead mouse. Lennie in his childlike mentality is always frustrating George to the point of anger.

Next, George is upset with Lennie because Lennie desires ketchup with his beans. George expresses frustration because he can't seem to please Lennie:

“Whatever we ain’t got, that’s what you want. God a’mighty, if I was alone I could live so easy. I could go get a job an’ work, an’ no trouble. No mess at all, and when the end of the month come I could take my fifty bucks and go into town and get whatever I want . . . An’ whatta I got,” George went on furiously. “I got you!”

No doubt, George does feel frustrated at having to care for someone like Lennie. Lennie has such childlike capabilities until he is always getting in trouble. This causes problems for George. He feels responsible for Lennie. He carries the burden of taking care of Lennie. George is frustrated with Lennie. If only he didn't have to care for Lennie, George's life would be easier. Still, George realizes that Lennie depends on him. He knows that his life would be even lonelier without Lennie. Also, he promised Lennie's aunt that he would take care of Lennie.

Even though George gets frustrated with Lennie, he always calms down and shows Lennie that he cares:

Because they have a relationship based on genuine affection, Lennie is willing to tolerate George’s abuses and George is willing to suffer the frustrations and inconveniences of taking care of a childlike Lennie.

George has been angry with Lennie ever since they had the trouble in Weed. This is the first occasion, however, in which the author has an opportunity to present a lot of exposition in the form of an angry diatribe. It should be kept in mind that Steinbeck intended to adapt his story into a stage play almost immediately. The book and the play came out the same year. Steinbeck intentionally used dialogue for exposition in the book because that made it easy to convert the book into a play. In a play there is no such think as exposition. The audience has to learn everything from what the characters say to each other. The audience even has to learn who these characters and what their relationships are from what they say. The exception is in a play like Our Town in which there is a narrator explaining everything to the audience.

Steinbeck chose to have George become angry at the campsite in the first chapter because the anger makes the scene more dramatic. But mainly it can be seen that George is explaining all about their relationship and about what happened with the girl in Weed. It is purely exposition, not real anger. George gets angry because Steinbeck makes him get angry. Steinbeck makes him get angry because he wants his character to present a lot of essential information but at the same time to make it feel dramatic. There is no real conflict between George and Lennie. Lennie offers to go off and live by himself, but George tells him to stay. When the blow-up is over, their relationship is exactly the same as it was before. 

What happened in the little town of Weed is of great significance. Lennie is starting to take an interest in girls. George doesn't realize that Lennie is dangerous until he sees the body of Curley's wife in the barn. It should be noted that George doesn't actually see what made the girl in Weed start screaming. He was some distance away. He has only Lennie's account of the incident--and Lennie is always lying to George, as he lies about the mouse in his pocket. It is also noteworthy that George is not present when Lennie ends up killing Curley's wife. George only sees the dead body and assumes that Lennie was trying to rape the girl and accidentally killed her.

Unlike George, who is consciously aware of his environment, Lennie is unaware of his surroundings and his behavior in general. Upon entering the clearing, Lennie almost walks over George. After entering the clearing, Lennie and George come to a pool and Lennie plops himself down and begins to drink too fast. George scolds him because he doesn't want Lennie to get sick. George scolds Lennie quite a bit in this novel. At times, it is out of exasperation. But most of the time, George is just trying to get through to Lennie to make sure he doesn't hurt himself or someone else. George is frustrated with Lennie because they had to leave their last job prematurely. George is also frustrated because he has to continue to repeat their plans for the future:

"That ranch we're goin' to is right down there about a quarter mile. We're gonna go in an' see the boss. Now, look- I'll give him the work tickets, but you ain't gonna say a word. You jus' stand there and don't say nothing. If he finds out what a crazy bastard you are, we won't get no job, but if he sees ya work before he hears ya talk, we're set. Ya got that?"

Since Lennie forgets, George feels compelled to continue telling him not to talk and to avoid any chance of an awkward social situation.

George has been angry at Lennie ever since that incident in the town of Weed. Lennie molested a girl on the main street in broad daylight, and the two men had to run for their lives. George is only expressing his anger now. This happens all the time between people. It often happens between married couples, for instance. One or the other explodes and vents a whole lot of issues and grievances in one harangue. George probably hasn't told Lennie off before because he knows Lennie is mentally handicapped and isn't responsible for his behavior. Furthermore, George doesn't think Lennie could understand him anyway. George took on a heavy burden when he promised Aunt Clara he would look after Lennie. For how long? He could be tied to this feeble-minded giant for thirty or forty years. George is like a volcano that will erupt periodically. The anger is always there because the burden and the resulting resentment and frustration are always there. Lennie is more of a liability than an asset. George is a "little guy" and Lennie may afford him some protection, not unlike a big watchdog, in the harsh world where men travel on freight trains, sleep in the open or in hobo jungles, and have to compete for low-level jobs as unskilled laborers. But Lennie is always getting them both fired, if not getting them into more serious trouble. Lennie's guilt rubs off on George, because has assumed responsibility for Lennie and knows Lennie is capable of causing trouble wherever he takes him. George's eruption of anger in the opening scene foreshadows what is bound to happen sooner or later. George wants to be free of his burden, whether he is conscious of the fact or not. When he finally kills Lennie in the last chapter, he has mixed feelings. Naturally he feels guilt, sorrow, and pity; but he also feels relieved. People keep changing. Friendships don't last forever. 

The first scene of Of Mice and Menserves as the exposition to John Steinbeck's novella of the social plight of the disenfranchised men of the Great Depression. Into a quiet clearing outside Soledad, two solitary men enter, the larger one following the other man in the shuffling, lumbering gait of a bear. After they set up camp, George Milton, the smaller man, cooks three cans of beans on the fire made from wood gathered by Lennie.

"There's enough beans for four men," George said.
Lennie watched him from over the fire. He said patiently, "I like 'em with ketchup."

Angrily, George informs Lennie that there is no ketchup, complaining that whatever Lennie wants, they do not have. He then launches into a tirade about how much trouble Lennie is and how he could get along so much better without him.

"I got you! You can't keep a job and you lose ever' job I get. Jus' keep me shovin' all over the country all the time. An that ain't the worst. You get in trouble. You do bad things and I got to get you out.....You keep me in hot water all the time."

This angry complaint foreshadows what occurs later in the narrative as Lennie does, indeed, get them into "hot water" with Curley when he crushes the shorter man's hand and on the ranch when he inadvertently breaks the neck of Curley's wife, who has flirted with him, asking him to touch her silken hair as she taunts him in the barn when all the other men are gone to town. 

The best example of how Steinbeck conveys the impression that George can easily get annoyed with Lennie is to be found in Chapter One, when the two men are getting ready to eat their last three cans of beans.

"There's enough beans for four men," George said.

Lennie watched him from over the fire. He said patiently, "I like 'em with ketchup."

"Well, we ain't got any," George exploded. "Whatever we ain't got, that's what you want. God a'mighty, if I was alone I could live so easy...."

Then George continues for a full page with the complaints and recriminations that have been building up ever since the Weed incident and have "exploded" because Lennie observed that he likes beans with ketchup. George is feeling that Lennie is too much of a burden for him to carry. If he were alone his life would be easy. But, he complains, Lennie keeps getting him into trouble. In Weed they had to run for their lives because Lennie had molested a girl and frightened her into thinking he was going to rape her (which is what might actually have happened if Lennie hadn't attracted a lynch mob by assaulting the girl in broad daylight on the main street of a very small town). Weed is about four hundred miles to the north of where George and Lennie are presently camping near Soledad, and the two men have been more or less on the run until now. George only knows what Lennie told him about the Weed incident, and Lennie (1) does not understand his own feelings, and (2) lies to George consistently. George describes a small part of the incident:

He took on the elaborate manner of little girls when they are mimicking one another. "Jus' wanted to feel that girl's dress--jus' wanted to pet it like it was a mouse-- Well, how the hell did she know you jus' wanted to feel her dress? She jerks back and you hold on like it was a mouse. She yells and we got to hide in a irrigation ditch all day with guys lookin' for us, and we got to sneak out in the dark and get outta the country. All the time somethin' like that--all the time."

When George finally kills Lennie at the same campsite in the last chapter, it will not be entirely an act of compassion. George would really like to free himself from Lennie. The big retarded man is becoming too much for him to handle. In Chapter One when George tries to take the dead mouse away, Lennie puts up a strong resistance. He is beginning to realize that he has a will of his own and doesn't have to do whatever George tells him. George's display of anger is extremely significant. It shows that he is in fact continually annoyed by this feeble-minded giant and foreshadows the so-called "mercy killing" which will end the story. George's outburst also foreshadows the trouble that Lennie will get into with Curley's wife at the ranch. 

In Chapter Two, after their interview with the boss, George expresses his annoyance again.

"So you wasn't gonna say a word. You was gonna leave your big flapper shut and leave me do the talkin'. Damn near lost us the job....Yeah, you forgot. You always forget, an' I got to talk you out of it....Now he's got his eye on us. Now we got to be careful and not make no slips. You keep your big flapper shut after this."

They would be in desperate straits if they lost that job. They are broke and have eaten the last of their food. George certainly has good cause to be annoyed. 

Lennie is frustrated because George doesn’t allow him to have pets.  He has trouble remembering things.  He is also frustrated when Curley picks on him, because he doesn’t understand what is happening. 

Before George and Lennie get to the ranch, they stop to rest and Lennie finds a mouse.  George knows he has it and makes him throw the dead mouse away, but this frustrates Lennie.  He wants to pet the mouse. 

Lennie's closed hand slowly obeyed. George took the mouse and threw it across the pool to the other side, among the brush. "What you want of a dead mouse, anyways?"

"I could pet it with my thumb while we walked along," said Lennie. (Ch. 1) 

Later, Lennie gets a puppy and the same thing happens.  He kills it by accident and Curley’s wife finds him stroking a dead puppy.  She doesn’t realize that his wanting to pet things gets him into trouble.  They were run out of Weed for him touching a lady’s dress.  He accidentally kills Curley’s wife too, breaking her neck because he wants to stroke her hair. 

Lennie also gets frustrated when he can’t remember things.  George looks out for him.  He knows where they are going and speaks for Lennie when they get there. 

"…You remember about us goin' in to Murray and Ready's, and they give us work cards and bus tickets?"

"Oh, sure, George. I remember that now." His hands went quickly into his side coat pockets. He said gently, "George... I ain't got mine. I musta lost it." He looked down at the ground in despair. (Ch. 1) 

George tells him he didn’t lose his work card, he just never had it.  He wouldn’t let him keep his own work card, because he would lose it.  Lennie doesn’t mind this though, because George is looking after him. 

Lennie gets into trouble again with Curley.  George tells him not to mess with Curley, because Curley wants trouble.  Lennie tries to listen, but Curley sees him smiling and picks a fight.  Frustrated, Lennie fights back when George gives him permission. 

George shouted over and over. "Leggo his hand, Lennie. Leggo. Slim, come help me while the guy got any hand left."

Suddenly Lennie let go his hold. He crouched cowering against the wall. "You tol' me to, George," he said miserably. (Ch. 3) 

Lennie doesn’t understand the world around him.  He is a mild-mannered, kind man.  However, he is very strong.  He was able to injure Curley badly just by hanging on to him.  He was frightened and frustrated by this incident too.

The character of Lennie in the novel Of Mice and Men, by John Steinbeck is not necessarily meant to appear miserable. Additionally, there is not enough information in the story that would help us conclude officially that he was, indeed, miserable. In fact, if you compare Lennie to George, Crooks, and many other in the novel, he may probably prove to be the least miserable of them all precisely because he does not know any better. Yet, there are several characteristics that Lennie possesses that would make a man with average intelligence feel quite miserable. Then again, Lennie is not a man with average intelligence.

The problem with Lennie is that he cannot control himself. He is extremely big and strong for his own good. He is also taller than his peers. To top it all, he is highly emotional and loses his temper to the point of hurting, breaking, and even killing by accident. Should a man with a higher level of intelligence go through this situation, his life would be miserable for sure. It would be no different than being a type of Dr. Jekyll and Mr. Hyde, or even a type of Incredible Hulk.

Yet, Lennie only goes as far as knowing that someone will be mad at him because he did "something" wrong. He does not know what, or the consequences of what he did, but he knows that he has messed up somehow. However, it is precisely this innocence what protects Lennie from becoming miserable: Unfortunately he makes everyone around him, especially George, miserable indeed. For Lennie is a danger to society, no matter how immature or mentally challenged he may be. This is the biggest tragedy of his life.