Something I thought of while watching "Worst Nightmare." I don't own NCIS...
Their bodies were always in sync. They moved together and their thoughts paralleled each other. When they were discussing new information, their arms always touched. The sparks between them jumped from their arms. Heat radiated in between them.
When they were together after work their chemistry was off the charts. Their bodies moved with each other; it was like they were one person when they were making love.
And when they were at work, they moved in sync. Their bodies were now used to being together, that while they were working their bodies automatically moved together. It was just a habit that neither of them wished to break.