A/N: I was bored. Boredom plus internet access equals drabbles, generally.
All living creatures are born with one heart. They are woefully incomplete.
It was a human myth, of course. Once humanity had been introduced to the universe at once, it had faded into obscurity - after all, the discovery of tetrapulmonary circulatory systems did tend to dampen such ideas a bit. The Doctor, though, couldn't help thinking that there was something to the concept; it would explain quite a lot.
Thus, they must seek out others, in order to have two hearts and be whole.
But Time Lords already have two hearts. Time Lords, he thinks, are complete by that very definition.
Maybe that's why they are so lonely - because they have no real need of others, they can last alone, without the descent into insanity. Time Lords are built to be alone.
He watches Rory and Amy together, as she laughs, pulling arms around his waist from behind, and pretends he doesn't feel a slight inward clench of jealousy.