  Boundary, defect, and interface RG flows, as exemplified by the famous Kondo
model, play a significant role in the theory of quantum fields. We study in
detail the holographic dual of a non-conformal supersymmetric impurity in the
D1/D5 CFT. Its RG flow bears similarities to the Kondo model, although unlike
the Kondo model the CFT is strongly coupled in the holographic regime. The
interface we study preserves $d = 1$ $\mathcal{N} = 4$ supersymmetry and flows
to conformal fixed points in both the UV and IR. The interface's UV fixed point
is described by $d = 1$ fermionic degrees of freedom, coupled to a gauge
connection on the CFT target space that is induced by the ADHM construction. We
briefly discuss its field-theoretic properties before shifting our focus to its
holographic dual. We analyze the supergravity dual of this interface RG flow,
first in the probe limit and then including gravitational backreaction. In the
probe limit, the flow is realized by the puffing up of probe branes on an
internal $\mathsf{S}^3$ via the Myers effect. We further identify the
backreacted supergravity configurations dual to the interface fixed points.
These supergravity solutions provide a geometric realization of critical
screening of the defect degrees of freedom. This critical screening arises in a
way similar to the original Kondo model. We compute the $g$-factor both in the
probe brane approximation and using backreacted supergravity solutions, and
show that it decreases from the UV to the IR as required by the $g$-theorem.
