Shapeley (Roscoe Karns)’s Timeline and Summary

Shapeley first appears ("Shapeley's the name, and that's the way I like 'em," meaning he likes women with curves) when Ellie sits next to him on a northbound bus as a way to avoid Peter.
But a few moments with Shapeley are enough to make Ellie realize that Peter's the far better traveling companion.
Shapeley comes on to Ellie, prompting Peter to approach and pretend to be her husband.
Shapeley apologizes for having been so direct—and so disgustingly forward—with Peter's "wife."
Later, Shapeley tries to apologize to Ellie, but she's not having it.
Reading a newspaper, Shapeley realizes who Ellie is. He threatens to reveal her identity, saying he'll split the $10,000 reward 50/50 with Peter.
Shapeley's scared away very easily when Peter talks as if he's a tough guy who knows other tough guys, one of them named "the Killer."