9. Her Life Was On Track
Unlike Rose Tyler, and many of the coveted companions that came before and after her, Martha Jones' life was pretty much right on track when she first encountered the Tenth Doctor back in Series 3. She wasn't necessarily looking for the same sort of escape route that her predecessor had been. While Rose was bored of her mundane 9 to 5 existence (and spent a lot of her time reaffirming just how much she hated it), Martha was in the middle of her exams and was already well on her way to becoming a qualified doctor until the Doctor fell out of the sky and threw an almighty spanner in the works. Not a laser spanner, though. That got stolen by Emmeline Pankhurst, the cheeky woman. Martha's fateful encounter with the titular Time Lord in Smith and Jones opened her eyes to a whole new world of adventure and she subsequently swapped her textbooks for the TARDIS for "just one trip" which, as it was always going to, soon escalated into many, many more. She was also caught up amidst an ongoing family feud which probably made the concept of a temporary break all the more appealing. She would've been quite happy to plod along, though - she was just an ordinary girl who happened to meet an extraordinary man who offered her a world of adventure like nothing she'd ever seen before. Let's face it, who in their right mind would say no to that?
