  In this paper, we study the asymptotic behavior of ground state solutions for
the nonlinear Choquard equation with a general local perturbation $$ -\Delta
u+\varepsilon u=(I_\alpha \ast |u|^{p})|u|^{p-2}u+ g(u), \quad {\rm in} \
\mathbb R^N,
  \eqno(P_\varepsilon)
  $$ where $N\ge 3$ is an integer, $p=\frac{N+\alpha}{N}$, or
$\frac{N+\alpha}{N-2}$, $I_\alpha$ is the Riesz potential and $\varepsilon>0$
is a parameter. Under some mild conditions on $g(u)$, we show that as
$\varepsilon\to \infty$, after {\em a suitable rescaling} the ground state
solutions of $(P_\varepsilon)$ converge to a particular solution of some limit
equations, and establish a sharp asymptotic characterisation of such a
rescaling, which depend in a non-trivial way on the asymptotic behavior of the
function $g(s)$ at infinity and the space dimension $N$. Based on this study,
we also present some results on the existence and asymptotic behaviors of
positive normalized solutions of $(P_\varepsilon)$ with the normalization
constraint $\int_{\mathbb R^N}|u|^2=a^2$. Particularly, we obtain the
asymptotic behavior of positive normalized solutions of such a problem as $a\to
0$ and $a\to \infty$.
