6. Human Nature/Family Of Blood
This is a great two part episode. It tells a well-rounded story exploring what the Doctor would be like if he were human. The story starts off with the Doctor and Martha being chased by the Family of Blood and in order to escape them, the Doctor transforms himself into a human being with his consciousness locked in a pocket watch. They end up in the year 1913 and the Doctor becomes a teacher at an all-boys school and Martha is a maid. The episode shows the level of trust that the Doctor has in Martha to see him through this situation, but the one thing he didn't factor in, was the possibility that he would fall in love. He falls for the school's nurse and they begin their relationship and Martha can do nothing to stop it. The Family ends up finding him and John Smith has to make the choice of staying hidden and letting innocent people die or giving up his life as a human. It's a heart wrenching decision for him to make. He gets a flash of what his life could be like as a human. A life filled with love, warmth and family. John Smith makes the conscience decision to leave that behind for the sake of saving others. It's painful, heartbreaking and Tennant's performance is flawless. What is particularly poignant is that the Doctor chose to hide in the first place. He knew how ruthless he could be and was trying to be merciful. In the end, he devised each member of the Family with their own personal hell. The Doctor was pissed! They wanted to live forever, well the Doctor made sure that they did that in complete torment. And the fact that he visits the little girl every year is eerie. He can be such a fun Doctor you forget that he has to have someone stop him sometimes.