Since Isaac isn't insane anymore I'm assuming when he sees Zeus he'll start questioning his sanity wondering if he's seeing things again,and Zeus probably taking it as an insult since he's real.
Wait what? Isaac isn't insane? Did I miss something? Isn't he still suffering from whatever he was suffering from during Dead Space 2? Did he get cured inbetween or what? If you are refering to the end of Dead Space 3, I don't know if you should assume that it happens after Dead Space 3, maybe it happens inbetween Dead Space 2 and 3.
I actually haven't played Dead Space 3 yet but I've been reading that he's not insane anymore. So yeah,and I assume it happen between Dead Space 2 and 3 too,well it could be the other way around? Instead of himself thinking he's going insane he'll probably just know that's he completely insane and be like **bleep** ZEUS! YOU'RE NOT REAL!!! However none of the stuff really match up does it?
Ok so this was made to finnaly end the stupid reasons for the stupid theory heres probably the best reason for it
Gameplay-wise, both InFAMOUS and Fat Princess rely heavily on duality with the colors red and blue representing different sides. In Fat Princess, you can choose either the Red Kingdom or the Blue Kingdom, and in InFAMOUS, Cole can become either Hero Cole, who is represented by the color blue, or Evil Cole, who is represented by the color red. Both also have a theme of greed, with Evil Cole being power hungry and Fat Princess always being hungry and demanding for cake.
I just gave you a kudo for enforcing the truth.