So I just recently got myself waist deep into the Whovian world. I do notice two things though. One, David Tennant is the best ever doctor. Like literally, the best. Second, the doctor chooses his companions very carefully. And I mean very. Each companion brings something different into the mix, and they're different from one another. That is for a reason. Some companions are there to serve as foils for the doctor, while others are there to provide a sharp contrast. Let's start with Rose. Personally, I did not like Rose all that much. Mainly, this was because she was stupid and did stupid things that the doctor specifically tells her not to do. But in this way she is pathetically human. As human beings, we are curious and impulsive and that can get us at times. But in this sense, she is also very emotional, and driven by her heart. She does what she thinks is right and what makes other people happy instead of what is supposed to be right despite hurting people. In doing so, she contrasts the doctor. She is who he isn't. She makes him more human, more emotional. And that is precisely why he fell in love with her. Now Captain Jack is flamboyant, also contrasting him. But Jack is brave in the face of real danger and plus he comes in handy at times. Captain Jack is what the doctor tries very hard not to be. Ok now I would think most people like Martha. She was my favorite. She was clever, and very astute. She could plan things out as well as the doctor, and she was a very useful companion who knew what was right. She was brave and she loved the doctor. But unfortunately, same repels. But her cleverness was why I believe she was chosen. She represented all the good things in the doctor: cleverness, kindness, and bravery. Now, the most important, is Donna Noble. The loudmouth, hilarious, but insanely human ginger. As the doctor always wanted to be. They're a perfect match, as she brings out the human in him and he brings out the logical being in her. They are foils of each other and it's pretty funny. She knows when to be serious and when to set the doctor straight, very audacious. But her fiery spirit and strong will is why she was an excellent companion. She is who the doctor wants to be.