Mambo

i.

They are not a couple. They have slept together, but will be always be just partners. Still, they retire at the same time and simultaneously refuse to give up their apartments.

ii.

Booth convinces Brennan to take a dance class. His charm smile, aged and wrinkled, still works. They are totally synchronized as they mambo. The instructor asks how long they've been married. They still trip over each other's words.

iii.

Eighty years of healthy living do not stop Booth's heart attack.

"Family only!" The doctor is firm. For the first time, Bones wishes that she had married him.