  Helicity, a measure of the linkage of flux lines, has subtle and largely
unknown effects upon dynamics. Both magnetic and hydrodynamic helicity are
conserved for ideal systems and could suppress nonlinear dynamics. What
actually happens is not clear because in a fully three-dimensional system there
are additional channels whereby intense, small-scale dynamics can occur. This
contribution shows one magnetic and one hydrodynamic case where for each the
presence of helicity does not suppress small-scale intense dynamics of the type
that might lead to reconnection.
