How does George's character change/develop throughout the story?quotes wanted if possible

In Of Mice and Men, George plays the
following roles:

Traveling Companion,
Caregiver, and Dreamkeeper for Lennie. Early in the novella, George must
care for Lennie's survival and basic needs (food, shelter).  The two are migrant
workers, and while George must find the jobs, Lennie is a capable worker.  Also, George
must remind Lennie of the Dream Ranch, and he tells the story of how Lennie will tend
the rabbits.  George also perpetuates the dream for
Candy.

Rogue Mercy Killer.
Later in the novel, George must resort to secret crime (stealing Carlson's gun) in order
to prevent Lennie from becoming the victim of vigilante revenge.  He re-tells the dream
to Lennie and shoots him, giving him a somewhat quick and relatively painless death.
 Throughout, George has used the Dream Ranch tale in order to pacify Lennie, and one
wonders if he ever believed it was possible.