This is one of my favorite shippy tropes. Characters who know each other so well that they can read each other’s minds and therefore act with unthinking synchronization. Extra points for when it’s displayed under extreme pressure.

Usually we see this in fight scenes. E.g. Huntingbird from Marvel's Agents of S.H.I.E.L.D. (with bonus bickering, hahahah):

Or Mako/Raleigh (Maleigh) from Pacific Rim (Mentally linked via machinery, although they had to demonstrate this kind of compatibility first.):


Or from The Incredibles (Helen and Bob Parr):

And then there are pairings who take this to a whole new level like Fitzsimmons (also from Marvel's Agents of S.H.I.E.L.D.). Co-dependent to start, and now independent after being separated several times-- and yet still very much connected.

( "You and Simmons are so tight. It's like you're psychically linked." )