  We study the backreaction effect of a large axion field excursion on the
saxion partner residing in the same $\mathcal{N}=1$ multiplet. Such
configurations are relevant in attempts to realize axion monodromy inflation in
string compactifications. We work in the complex structure moduli sector of
Calabi-Yau fourfold compactifications of F-theory with four-form fluxes, which
covers many of the known Type II orientifold flux compactifications. Noting
that axions can only arise near the boundary of the moduli space, the powerful
results of asymptotic Hodge theory provide an ideal set of tools to draw
general conclusions without the need to focus on specific geometric examples.
We find that the boundary structure engraves a remarkable pattern in all
possible scalar potentials generated by background fluxes. By studying the
Newton polygons of the extremization conditions of all allowed scalar
potentials and realizing the backreaction effects as Puiseux expansions, we
find that this pattern forces a universal backreaction behavior of the large
axion field on its saxion partner.
