Pairing: Tenth Doctor/Jack Harkness
Summary: Of course Jack had noticed, right from the start: the way the Doctor would turn his head that particular way, the way he'd brush off hands that tried to curl around his skull, that touched the back of his neck. The way he was guarding himself, from what Jack didn't know.
A/N: Written for the prompt: "Alien biology and sexuality that really differ from humans'. Maybe something more mental-oriented?"
( Borrowed Time )