  Let $F_n$ be a free group of finite rank $n \geq 2$. We prove that if $H$ is
a subgroup of $F_n$ with $\textrm{rk}(H)=2$ and $R$ is a retract of $F_n$, then
$H \cap R$ is a retract of $H$. However, for every $m \geq 3$ and every $1 \leq
k \leq n-1$, there exist a subgroup $H$ of $F_n$ of rank $m$ and a retract $R$
of $F_n$ of rank $k$ such that $H \cap R$ is not a retract of $H$. This gives a
complete answer to a question of Bergman.
  Furthermore, we provide positive evidence for the inertia conjecture of Dicks
and Ventura. More precisely, we prove that $\textrm{rk}(H \cap \textrm{Fix}(S))
\leq \textrm{rk}(H)$ for every family $S$ of endomorphisms of $F_n$ and every
subgroup $H$ of $F_n$ with $\textrm{rk}(H) \leq 3$.
