- Just prior to the opening scene, George and Lennie had to leave the previous town because Lennie stroked a girl's soft dress (because it was soft, and he likes soft things), and when he petted too hard, the girl accused him of rape. They were forced to hide in an irrigation ditch all day because men were looking for them.
- When he was a child, Lennie liked to stroke soft things and often picked up mice for this reason. They'd try to bite him and he'd pinch their heads, killing them.
- Lennie's aunt once gave him a rubber mouse to play with, but he didn't like it because it wasn't soft.
- They had worked together on a ranch in Weed.
- When they were kids, George would give Lennie all the ketchup he wanted.