Orochimaru was opointed the fith hokage by Minato after Orochimaru saved Minatos life many times. And the villagers were starting to get to him as they all kept saying things like "your to young!" And " your just a jonin you don't deserve to be hokage!". Orochimaru isn't as wicked as he used to be and doesn't conduct experiments on anyone anymore. Orochimaru is a lot nicer as well. Your against Orochimaru becoming hokage tho but it has already happened and nothing can change now.

you are out in the forest when an anbu shows up

Anbu: you have been called by lord 5th. He would like to see you right away!