She couldn't help thinking how well they complemented each other.

He a fighter, a man of action; she a diplomat, words her chosen weapon.

He an extrovert, at home in others' company; she a loner, by both inclination and necessity.

He playful, mischievous, yet possessed of a deadly serious streak; she composed, authoritative, with a lurking undercurrent of good humor.

Substitute 'complete' for 'complement' – she couldn't help thinking that either.

FIN