  At high energy densities, fivebranes are populated by a Hagedorn phase of
so-called "little strings", whose statistical mechanics underlies black
fivebrane thermodynamics. A particular limit of this phase yields BTZ black
holes in $AdS_3$, leading us to the idea that in this context fuzzballs and
highly excited little strings are one and the same. We explore these ideas
through an analysis of D-brane probes of fivebrane supertube backgrounds.
String theory dynamics on these backgrounds is described by an exactly solvable
null-gauged WZW model. We develop the formalism of null gauging on worldsheets
with boundaries, and find that D-branes wrapping topology at the bottom of the
supertube throat are avatars of the "long string" structure that dominates the
thermodynamics of the black hole regime, appearing here as excitations of
supertubes lying near but slightly outside the black hole regime.
