Two‐and‐one‐half dimensional magnetostatic and electromagnetic particle simulations of time‐varying magnetic x points and the associated plasma response are reported. The stability and topology depend on the geometry, irrespective of the plasma &bgr;. The electrostatic field and finite Larmor radius effects play an important role in current penetration and shaping of the plasma flow. The snapping of the field lines, and dragging of the plasma into, and confinement of the plasma at, an o point (magnetic island) is observed. Magnetic island coalescence with explosive growth of the coalescence mode occurs and is accompanied by a large increase in kinetic energy and temperature as well as the formation of hot tails on the distribution functions.