Which character is mice and which is men?"Of Mice and Men"
In the case of Of Mice and Men, Lenny would most probably represent the mice in the title, while George would represent the men. It is ironic to see this because of Lenny's large size, however his behavior cannot qualify as that of a man because of his naivete and inability to understand nor cope well i social situations. George, however, must step up and take on the difficult task of killing Lenny in order to save him from the mob that is coming for him. His actions show courage, selflessness (in that he is willing to live his life knowing that he is the one who killed Lenny just so that Lenny will not have to face the horrors of the ensuing mob), and loyalty (he has committed a crime, murder, to save his friends and is thus putting himself on the line).
Within the story, symbolically, the character of George would be representing the men, while Lenny represents the mice.
Lenny is the simple character who holds the dead mouse, killed by his own hand from petting it too hard. He needs to be taken care of, constantly helped out of the serious situations he gets into because of his strength.
George is Lenny's friend and literally acts as his custodian. He looks after him like a brother. George protects Lenny and runs away with him to save him from the authorities. George takes charge of the situation whenever Lenny gets into trouble.
It isn't that one character is mice and one is men, but rather, the title comes from a Robert Burns poem. It means that all plans—the plans of mice and the plans of men—can go astray. The poem is "To a Mouse," and the lines are as follows: "The best laid schemes o' Mice an' Men,
Gang aft agley,
An' lea'e us nought but grief an' pain,
For promis'd joy! "
As gbeatty said, there is no specific mouse or man. The quote from "To a Mouse" ("The best laid schemes o' Mice an' Men,
Gang aft agley") is best paraphrased as follows: The best laid schemes of mice and men often go awry. We can interpret this as the theme of Of Mice and Men. George and Lenny had a plan to live on their fantasy ranch and that plan went awry.