Ruth was born with perhaps something more than the normal tendency to be envious and petty.
But these qualities might never have shown themselves conspicuously had there been no Susan for her to envy.

The very qualities that made Susan lovable reacted upon the pretty, pert blond cousin to make her the more unlovable.

Again and again, when she and Susan were about to start out together, and Susan would appear in beauty and grace of person and dress, Ruth would excuse herself, would fly to her room to lock herself in and weep and rage and hate.

And at the high school, when Susan scored in a recitation or in some dramatic entertainment, Ruth would sit with bitten lip and surging bosom, pale with jealousy.
Susan's isolation, the way the boys avoided having with her the friendly relations that spring up naturally among young people these gave Ruth a partial revenge.

But Susan, seemingly unconscious, rising sweetly and serenely above all pettiness-- Ruth's hatred deepened, though she hid it from everyone, almost from herself.