Athena Deceives Him, A Lot
The goddess Athena serves as a guiding force and an ally within Olympus to Kratos throughout the first two games, ensuring he has a chance at victory while also guiding him along the path to becoming the next god of war after defeating Ares. She even steps in and sacrifices herself when he is about to kill Zeus, hoping to keep him from killing his own father and adding to his already lengthy list of sins and regrets.
At the same time though, she frequently lies to and misleads him in order to accomplish her own goals. Along with letting him believe killing Ares would free him from his past mistakes, she manipulates him into killing the rest of the gods so that she can take all of their power for herself, leaving him with no one and nothing he can trust by the end of the original trilogy.