Board Thread:General Discussion/@comment-71.187.183.141-20151221025436/@comment-26397825-20151221062347

I kind of always figured she was having one last hang out with her sister before Yang went off to Beacon. Yang ditched her for the night so she could chase a lead, so Ruby went 'Well, I'll check out the shops while Yang's off doing stuff.' She found the Dust shop, found the weapons magazine, and the rest, as they say, is history.

A similar kind of story could have happened during the Yellow Trailer. Ruby's probably used to being ditched by her sister on random nights, and just does her own thing.