1. What is it?

Cruelty is the unnecessary harsh treatment of an individual or animal by another.

In literature, cruelty is often done by a person in power to a person without power.

2. How is it made?

3. Examples in literature

My Last Duchess 
by Robert Browning

That’s my last Duchess painted on the wall,
Looking as if she were alive. I call
That piece a wonder, now: Fra Pandolf’s hands
Worked busily a day, and there she stands.
Will’t please you sit and look at her? I said
“Fra Pandolf” by design, for never read
Strangers like you that pictured countenance,
The depth and passion of its earnest glance,
But to myself they turned (since none puts by
The curtain I have drawn for you, but I)
And seemed as they would ask me, if they durst,
How such a glance came there; so, not the first
Are you to turn and ask thus. Sir, ’twas not
Her husband’s presence only, called that spot
Of joy into the Duchess’ cheek: perhaps
Fra Pandolf chanced to say “Her mantle laps
Over my lady’s wrist too much,” or “Paint
Must never hope to reproduce the faint
Half-flush that dies along her throat”: such stuff
Was courtesy, she thought, and cause enough
For calling up that spot of joy. She had
A heart—how shall I say?—too soon made glad,
Too easily impressed; she liked whate’er
She looked on, and her looks went everywhere.
Sir, ’twas all one! My favour at her breast,
The dropping of the daylight in the West,
The bough of cherries some officious fool
Broke in the orchard for her, the white mule
She rode with round the terrace—all and each
Would draw from her alike the approving speech,
Or blush, at least. She thanked men,—good! but thanked
Somehow—I know not how—as if she ranked
My gift of a nine-hundred-years-old name
With anybody’s gift. Who’d stoop to blame
This sort of trifling? Even had you skill
In speech—(which I have not)—to make your will
Quite clear to such an one, and say, “Just this
Or that in you disgusts me; here you miss,
Or there exceed the mark”—and if she let
Herself be lessoned so, nor plainly set
Her wits to yours, forsooth, and made excuse,
—E’en then would be some stooping; and I choose
Never to stoop. Oh sir, she smiled, no doubt,
Whene’er I passed her; but who passed without
Much the same smile? This grew; I gave commands;
Then all smiles stopped together. There she stands
As if alive. Will’t please you rise? We’ll meet
The company below, then. I repeat,
The Count your master’s known munificence
Is ample warrant that no just pretence
Of mine for dowry will be disallowed;
Though his fair daughter’s self, as I avowed
At starting, is my object. Nay, we’ll go
Together down, sir. Notice Neptune, though,
Taming a sea-horse, thought a rarity,
Which Claus of Innsbruck cast in bronze for me!

Jane Eyre 
by Charlotte Brontë

Excerpt from Chapter XXVII:

I did. Mr. Rochester, reading my countenance, saw I had done so. His fury was wrought to the highest: he must yield to it for a moment, whatever followed; he crossed the floor and seized my arm and grasped my waist. He seemed to devour me with his flaming glance: physically, I felt, at the moment, powerless as stubble exposed to the draught and glow of a furnace: mentally, I still possessed my soul, and with it the certainty of ultimate safety. The soul, fortunately, has an interpreter—often an unconscious, but still a truthful interpreter—in the eye. My eye rose to his; and while I looked in his fierce face I gave an involuntary sigh; his gripe was painful, and my over-taxed strength almost exhausted.
“Never,” said he, as he ground his teeth, “never was anything at once so frail and so indomitable.  A mere reed she feels in my hand!” (And he shook me with the force of his hold.) “I could bend her with my finger and thumb: and what good would it do if I bent, if I uptore, if I crushed her? Consider that eye: consider the resolute, wild, free thing looking out of it, defying me, with more than courage—with a stern triumph. Whatever I do with its cage, I cannot get at it—the savage, beautiful creature! If I tear, if I rend the slight prison, my outrage will only let the captive loose. Conqueror I might be of the house; but the inmate would escape to heaven before I could call myself possessor of its clay dwelling-place. And it is you, spirit—with will and energy, and virtue and purity—that I want: not alone your brittle frame. Of yourself you could come with soft flight and nestle against my heart, if you would: seized against your will, you will elude the grasp like an essence—you will vanish ere I inhale your fragrance. Oh! come, Jane, come!”
As he said this, he released me from his clutch, and only looked at me. The look was far worse to resist than the frantic strain: only an idiot, however, would have succumbed now. I had dared and baffled his fury; I must elude his sorrow: I retired to the door.
“You are going, Jane?”
“I am going, sir.”
“You are leaving me?”
“Yes.”
“You will not come? You will not be my comforter, my rescuer? My deep love, my wild woe, my frantic prayer, are all nothing to you?”