T-branes and monopole deformations

T-branes are exotic bound states of D-branes, characterized by mutually non-commuting vacuum expectation values for the worldvolume scalars. We study T-branes in M-theory by probing the geometry with an M2-brane, finding that the effect of a T-brane is to deform the membrane worldvolume superpotential with monopole operators. The dynamics of the resulting theory can be studied using the (dimensional reduction of the) S-dual description of N=2 SU(N) SQCD with 2N flavors in four dimensions.