The first ally of the game John encounters, Bonnie MacFarlane saves Marston’s life by getting him medical attention after he is wounded by Bill Williamson.
If not for John’s wife Abigail, Bonnie surely would have become the love interest of the game. It’s kind of implied that Bonnie has feelings for John despite his marriage, even suspected by Abigail herself. It would be interesting to see if John crossed paths with a young Bonnie during his outlaw days, coming across her during a bank robbery or meeting the underage girl in a bar many years before, wooing her with his bad boy ways (the sly dog). It could be shown that this is where Bonnie’s shielded affection for John began, giving more explanation as to why she helped him in the beginning of the first game.
The second game could be an opportunity to show a more vulnerable Bonnie, where her brothers are still alive and before she had to step up in the harsh responsibilities that the Wild West thrusts upon everyone.