Ruby didn't understand her vampire companion. Sometimes, Ash was like a puppy at her beck and call, such as when he fed her food as she drove or handed her gardening supplies. Other times, he gave off a frightening aura.
She wondered what it was that made him that way but had her suspicions about what he talked about with Blair and why he needed to make a lot of money really fast. Something bad must have happened to him.
The closest vampire coven she had heard of was further north so she didn't know much about how they worked aside from the fact that they tended to stick with their own. A lone vampire in a destroyed castle wasn't normal.
If she had to guess, Ash was on the run just like she was. Maybe that sense of solidarity was why she proposed to help him longer than she originally planned.