Alphys / Undyne (Undertale), of course (although that may not quite count--that one's practically canonical.)
Papyrus / Mettaton (Undertale)
Asriel / Chara / Frisk (Undertale)
Bashir / Garak (DS9)
the four road-tripping guys from FFXV (I don't remember all their names but I'm sure they all fuck each other)