Written for a friend who has not yet seen past Amy and Rory. So sadly, no Clara.
The Doctor is a very lonely person. I've known this practically since the beginning of time. He is always running, never looking back, never staying. And there are people that may run with him. His companions. They keep him happy, lift his loneliness. But it can never last for long. He will outlive them all by eternity, no matter how long they want to stay with him. And when they leave him, by death, tragedy, or choice, it always breaks his two hearts. Shatters them. And he seeks out new companions to dull the pain, to try and become happy again. And the cycle starts over again, will always continue until the Doctor is gone.
Amy and Rory. The Ponds, as he affectionately refers to them as. I have observed that the Girl who Waited and the Last Centurion have a deep love for each other. And when seeing this, I knew Amelia Pond would eventually have to choose between Rory and the Doctor. And it saddened me, because the Doctor was at one of the happiest times of his life. The love between these three was practically tangible. They were simply a team. The best team I have ever seen. And I believe the Doctor knew that as well. Brave Amy and Rory have devoted their lives to the Doctor, became his true friends. They have stuck by him, through the Weeping Angels to the Silence to even the oddity of Melody Pond. But all of the companions must eventually leave and shatter the Doctor. And the fates of the Ponds did indeed shatter him. As soon as I heard, "Raggedy Man... goodbye!" And Amy had chosen Rory, to be with him. My heart did to seem to shatter. If I could, I would have sobbed with him. His most cherished friends. Gone.
Donna Noble. I am forever indebted to this woman. She healed the Doctor as no other being could. By being a best friend to him. Her sharp tongue and wit made a perfect match for him. She was not afraid to be friendly with him or to speak to him in a way that not many companions ever have. She spoke her mind and her opinion. Which, were both powerful, and oftentimes loud. I was astonished when she inherited the knowledge of the Doctor. But as I already knew from past experience, a human could not handle this kind of power. No matter that the Doctor dubbed her 'The most important woman in all creation,' Donna was still a human, her brain not suited for what she was inheriting. The DoctorDonna. A human with Time Lord power. It would have consumed her, if the Doctor had not saved her. And in saving her, he lost her. Donna lost her memories of her adventures, of the beings she had saved. And it could never be restored. As my Doctor did, I felt such loss as well. He was broken once again.
Of all of his companions, I feel the Doctor should have appreciated Martha Jones more than he showed to her. I believe he was hurting very badly and did not see how he was treating her. But I did, and I knew she would be the one to leave. Martha was a very strong companion, intelligent as well. She loved him, of that I was certain of. I later learned that she eventually found the happiness she deserved. Martha was average, but so exceptional in her own way. She saved my Doctor during the one year takeover of Earth, giving hope to the planet. Her support and loyalty showed for the Doctor then, as it always will.
The Valiant Child. The one who changed my Doctor for the better. As Rose Tyler will always be part of him, she will also be a part of me. As I am a part of her. The Bad Wolf. She was so different from the Doctor when they first met, but they were alike as well. They reminded me of the Earth yin and yang. They seemed to be two halves of a whole. Happiness was constantly between them, always flowing. She loved him more than she loved herself. And she was willing to give up everything and anything for him. And I know, that he loved her dearly as well. Loved her more than he had anything else in his long life. But the Doctor was living in a fantasy. Young Rose was still human. And when she was taken from him, he was crushed. And I was as well, for the girl who selflessly merged with me to save the Doctor. For a long time, I was alarmed that he wouldn't be able to move on this time. And he probably wouldn't have, if not for the companions that kept him going. When she finally did appear again, I remember seeing hope in the Doctor's face. Hope and pure happiness. Only to see him give her up for a human Doctor that could live with Rose. I always grieve for these two, who could never be.
The Doctor is always running. And his companions get lost along the way. They can never truly stay with the Doctor, as he could stay with them. It is a tragedy for this madman in a blue box, who does so much for the entire universe. But no matter how much he loses his companions, I will always be there for him. His constant friend, crutch and home. The TARDIS.