They

He - he was so smart
he had a brain in place of his heart
She - she was so kind
she had a heart in place of a mind
and They- they were perfect
one made up for the other's defect

Was telling S he was born with two brains and no heart and I was born with no brains and two hearts, and thus on a rainy Monday, we made this song together :-) The first of many to come