the more massive object is also “orbiting” the less massive one at a much slower rate. They are orbiting the center of gravity of the system. it does seem unlikely that small bodies could capture each other because they have very low escape velocities. I’d guess they were of the same objectn shattered in an impact and drifted apart due to other gravitational influences and even solar wind.
That is a definite possibility, although I'm not so sure that it was an impact that caused them to separate. I would think an impact would have more scattered the debris.
However, I guess an impact could have at least loosened some material, resulting in the smaller piece slowly separating at some later time, perhaps with gravitational help from the Sun or even other planet that it had possibly passed close to.