  Bound states of 7-branes known as 'T-branes' have properties that defy usual
geometric intuition. For instance, the gauge group of n coincident branes may
not be U(n). More surprisingly, matter may show up at unexpected loci, such as
points. By analyzing T-branes of perturbative type IIB string theory in the
tachyon condensation picture we gain the following insights: In a large class
of models, the tachyon can be diagonalized even though the worldvolume Higgs
cannot. In those cases, we see the structure of these bound states more
manifestly, thereby drastically simplifying analysis of gauge groups and
spectra. Whenever the tachyon is not diagonalizable, matter localizes at
unexpected loci, and we find that there is a lower-dimensional brane bound to
the 7-brane.
