In Of Mice and Men by John Steinbeck, who does Candy express his feelings to?

Candy mostly expresses his feelings to George. When he first meets George and Lennie, he tells them all about each of the characters on the ranch and his feelings about the various workers. He informs George that he thinks Curley's wife is a "tart" and Curley a bully.

In Chapter Three, after Carlson shoots his dog, he reveals his fears to George about what will happen to him when he can't swamp out the bunks...

Candy mostly expresses his feelings to George. When he first meets George and Lennie, he tells them all about each of the characters on the ranch and his feelings about the various workers. He informs George that he thinks Curley's wife is a "tart" and Curley a bully.

In Chapter Three, after Carlson shoots his dog, he reveals his fears to George about what will happen to him when he can't swamp out the bunks anymore. He even offers to contribute all of his money to the farm which George dreams of buying. He tells George,

“I got hurt four year ago,” he said. “They’ll can me purty soon. Jus’ as soon as I can’t swamp out no bunk houses they’ll put me on the county. Maybe if I give you guys my money, you’ll let me hoe in the garden even after I ain’t no good at it. An’ I’ll wash dishes an’ little chicken stuff like that. But I’ll be on our own place, an’ I’ll be let to work on our own place.” He said miserably, “You seen what they done to my dog tonight? They says he wasn’t no good to himself nor nobody else. When they can me here I wisht somebody’d shoot me. But they won’t do nothing like that. I won’t have no place to go, an’ I can’t get no more jobs. I’ll have thirty dollars more comin’, time you guys is ready to quit.” 

In an example of foreshadowing, Candy also admits to George that he should have shot his dog himself rather than let Carlson do it. These words must be on George's mind after Curley's wife is discovered dead.

In Chapter Four, while Candy is in the barn with Crooks and Lennie, Curley's wife enters. When she won't leave and has nothing but insults for the men, Candy explodes and expresses his hopes for his future with George and Lennie as well as his feelings about the girl. He says,

“You ain’t wanted here. We told you you ain’t. An’ I tell ya, you got floozy idears about what us guys amounts to. You ain’t got sense enough in that chicken head to even see that we ain’t stiffs. S’pose you get us canned. S’pose you do. You think we’ll hit the highway an’ look for another lousy two-bit job like this. You don’t know that we got our own ranch to go to, an’ our own house. We ain’t got to stay here. We gotta house and chickens an’ fruit trees an’ a place a hunderd time prettier than this. An’ we got fren’s, that’s what we got. Maybe there was a time when we was scared of gettin’ canned, but we ain’t no more. We got our own lan’, and it’s ours, an’ we c’n go to it.” 

Candy also expresses his profound disappointment when George indicates that the dream of the farm is over in Chapter Five. He asks George,

“You an’ me can get that little place, can’t we, George? You an’ me can go there an’ live nice, can’t we, George? Can’t we?” 

George's response is basically that without Lennie he wouldn't want to go to the farm. Candy's hopes and dreams, like George's, are dashed by the irrational acts of the mentally challenged Lennie. The reader may presume that Candy lives out his life in loneliness on the ranch.