PAIRS
This shows the paths of some specks of colour as they emerge from several moving bodies. Each body belongs to one of four breeds: those that emit teal specks of colour, those that emit orange ones, those that emit white ones or those that emit violet ones. Each breed, in turn, belongs to one of two pairs. Each body accelerates with a constant magnitude of acceleration towards the closest body among those belonging to the other breed in the pair to which its own breed belongs.
Meanwhile, each body emits specks of the appropriate colour in the direction opposite to its acceleration. All the specks of colour move at the same speed and fade as they move.