What characteristics do the underdogs have in common? Candy, Curley's wife, and Crooks?Of Mice and Men by John Steinbeck

In John Steinbeck's novella, Of Mice and
Men, the characters Candy, Curley's wife, and Crooks are all social pariahs,
isolated by some shortcoming.  For old Candy it is age and disability, for Crooks, it is
his race, and for Curley's wife, it is her gender and social
status.

Having been injured, Candy is unable to work
outside the bunkhouse.  Like the old dog that he owns, he stays in one spot and sweeps
and straightens it.  Crooks, too, stays at night alone in the barn with the mules,
having no human company.  And, Curley's wife is isolated, too, as their are no women
with whom she could socialize.  As a consequence, she wishes to talk with the men, but
they reject her as dangerous since she is married to the son of the ranch's
owner. 

Each character voices his/her anxiety. Crooks tells
Candy and Lennie,

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A guy needs somebody--to be near him....Aguy goes
nuts if he ain't got nobody.  Don't make no difference who the guy is,  long's he's with
you.

 Candy worries that the
ranch owner will get rid of him when he is no longer useful. He remarks
to Crooks,

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Everybody wants a little bit of land, not much. 
Jus' som'thin' that was his. Somethin' he could live on and there couln't nobody throw
him off of it.

Curley's wife,
too, expresses her dismay at being alone. Standing in the doorway, she tells Candy,
Crooks, and Lennie,

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Ever'body out doing' som'pin'.  Ever'gody! 
An'what am I doin'?  Standin' her talkin' to a bunch of bindle stiffs...an' likin' it
because they ain't nobody
else.

Lonely and insecure and
isolated, the men and Curley's wife share lives of "quiet desperation" as Henry David
Thoreau once remarked.