At the onset of X-Men: Apocalypse, Magneto, Storm, Psylocke and Archangel all appear to be fairly lost souls, from what we've gleaned from interviews. Enough to be easily persuaded by a powerful figure like En Sabah Nur to join his cult-like crusade. If there is a fair amount of manipulation and coercion involved in persuading them to become his Four Horsemen, it allows for the opportunity to redeem all of these characters by the end of the movie. Let's not forget that Storm, Angel and Psylocke are X-Men in the source material: it makes perfect sense that Singer would want to leave them as such by the time the credits roll. If Apocalypse has actually been brainwashing them into being his horsemen - don't forget Professor Xavier's line in the trailer, "he can control all of us" - then it could transpire before the final battle that they wrest free of that control and assist our intrepid heroes in fighting the big blue b*stard.
Cinephile since 1993, aged 4, when he saw his very first film in the cinema - Jurassic Park - which is also evidence of damn fine parenting. World champion at Six Degrees of Separation. Lender of DVDs to cheap mates. Connoisseur of Marvel Comics and its Cinematic Universe.