Alive, and very confused as to why his phone call with Mark went so bizarrely. One of the Alternates took on Cesar's face and voice to troll Mark while they waited for him to show up to Cesar's house so they could follow him home. Poor Cesar assumed it was a break-in and drove his mom (Who fainted after one of the Alternates screamed at her) to the hospital, then called Mark to ask him to check out the security cameras.
Alive, and in on the Alternate's plan. The Alternates went to Cesar's house and partied there, so Cesar pawned them off on Mark by tricking him into coming to Cesar's house. While Cesar seems to be just as confused about the phone interference as Mark is, he could just be lying: his protests didn't seem to be all that convincing.
An Alternate his entire life. This is a bit more on the bizarre side, but perhaps "Cesar Castle" was never a real person to begin, just an Alternate under a fake name. When Cesar screams at his mom not to turn on the light, it's because he doesn't want her to see what he really looks like. The party he's throwing at Mark's house is really just his way of explaining the whole situation to Mark in a casual way.
