Dominant Ne: Connections are a must in the Doctor’s world. He enjoys any opportunity to blow people’s socks out of the water by impressing them with an incredibly out-of-the-box solution. The Doctor is energized and excited by new ideas and often jumps into hefty trails of thoughts leading to more thoughts leading to more thoughts etc. He views everything in terms of the big picture, both in terms of time, space and morality. He looks for the meaning behind what is in front of him, rather than simply accepting evidence at face value. He is fairly intuitive about people/aliens and is able to use his understanding of them to his advantage in sticky situations. He is perfectly capable of holding two conflicting “truths” in his head, and doesn’t allow that to stop him from reaching conclusions.
Auxiliary Fi: The Doctor is a charmer who draws people to him and his adventures like magnets. When he gets excited, it comes out in a hurricane of passion so that it rubs off on other people, making them excited about his ideas as well. The Doctor hides his feelings and it takes loads of coaxing to get him to really explain any of his past to anyone. He feels deeply and intensely, though he doesn’t always want to. He believes in universal moral principles, but never relies on anyone else to know what is right. He needs people and feels extremely lonely when he doesn’t have a companion. He doesn’t always understand other people’s feelings because he’s preoccupied with his own problems (doesn’t notice that Martha loves him because he’s still fixated on Rose). At times, his view of others can be a bit too objective, and as a result, can come off as unfeeling and rude.
Tertiary Te: Although open to possibility, the Doctor believes in absolutes. His logic is not internally based, but rather, based on external evidence in his environment (people often mistake him as a Ti because his logic is different than everyone else’s, but… I would argue that he simply has a greater understanding than other people. His logic is based on external knowledge of the entire universe). He’s able to put aside his own personal feelings in order to make harsh big-picture decisions because he values other people more than himself. He is incredibly focused when trying to figure out a race’s system and motivations. His solutions to problems are always creative (feeding off of Ne) because he relies on ideas before logic. The Doctor is quick to take action once he figures out what needs to be done, but is able to improvise when he needs to.
Inferior Si: When he thinks about the past, the Doctor relives the emotional experiences associated with said memories. As a result, he usually attempts to avoid thinking about painful memories, dwelling instead in the realm of Ne possibility. Though the Doctor loves to explore new ideas and places, he does like to keep a certain amount of constancy in his life –such as always having someone (pretty much always a female someone) to travel with. He has a vast store of knowledge that aids him in decision making, and he relies heavily on this knowledge. When he encounters something vastly new, he is excited, but suspicious.
I’ve seen Ten mistyped as an ENTP simply because he’s so intelligent and generally rational. Unfortunately for those people, he uses FiTe, not TiFe.