John Cusack.. Do you really want to see his shoulder hunched/slack jawed amazement at Abra's weirdness ??
I promise you the director will not be able to beat this standard reaction out of him with a stick.
The builing of suspense lies in the actors ability to reflect - in increments - the growing realization that the horrors Abra is gaining knowlegde of, are very true.
Cusack doesent have increments he has cow-stunned furrowed brows.
Casey Affleck would be fantastic. Harry Treadaway from Penny Dreadful and the upcoming Mr. Mercedes adaptation would be good too. Other possibilities - James McAvoy, James Badge Dale - who can be seen in Spectral on Netflix, Elijah Wood - 'nuff said, & Aden Young who is fantastic in Rectify.