  We study two-dimensional SQED viewed as the world-volume theory of a D-string
in the presence of D5-branes with non-zero background fields that induce
attractive forces between the branes. In various approximations, the low-energy
dynamics is given by a hyperKahler, or hyperKahler with torsion, massive
sigma-model. We demonstrate the existence of kink solutions corresponding to
the string interpolating between different D5-branes. Bound states of the
D-string with fundamental strings are identified with Q-kinks which, in turn,
are identified with dyonic instanton strings on the D5-brane world-volume.
