  We study the monodromy of Painlev\'e VI equation from a dynamical point of
view. This is applied to the description of bounded orbits, and to a proof of
the irreducibility of Painlev\'e VI equation in the sens of Casale and
Malgrange. On our way, we compute the entropy of each element of the monodromy
group, and we precise the dictionary between character varieties and Painlev\'e
equations.
