Martha Jones is a brilliant companion and one I’ve grown to like and appreciate even more over time.
As a Doctor/Rose shipper I did get tired of her mooning over the Doctor and I think it was a poor writing decision to have that as part of her character because it just made it all the more easier to compare her to Rose – especially for someone like me who Rose was the first companion I’d seen. Martha’s love of the Doctor was sometimes the character trait that outshined her better and more interesting qualities.
When we first meet her she’s training to be a doctor and clearly thinks outside the box, being the one to first suggest that there must be oxygen around them even though the hospital was on the moon, because doors and windows were hardly airtight. I really liked how her medical training is used throughout the series and how she’s shown to be kind-hearted and eager to help anyone, even aliens who aren’t humanoid and clearly have a very different physiology to what she’s used to.
Martha is brave and funny and I love how her family drama is always there and brushes up against her adventures with the Doctor. She has an older sister and a younger brother and Martha fits a lot of the middle child tropes with her trying to be a peacekeeper in the family feuds, especially between her divorced parents. The family dynamics for the companions is one of my favourite things in the RTD era and how exasperated Martha sometimes gets with them is very relatable.
How much her family means to her makes Martha’s choice in the finale almost seem obvious and I love how she chooses to put herself and her family first after going through hell for a year. Because Martha Jones saved the world, she saved the Doctor, and she had to do it pretty much all on her own while the Doctor and her family were held hostage by a mad man. Martha then joining UNIT and becoming almost a soldier does also seem like the logical next step for her, though it also shows the affect the Doctor has on people, turning them into weapons to fight his battles for him.