I finally beat God of War II about a week ago, and the storyline raised some questions for me on who was who, and the relationships between the characters. So I do what I do when I want to know something, open Mozilla Firefox and type "wiki" in the address bar.
I browsed Wikipedia for "King Theseus", clicking links and placing them in tabs. This helped to up my knowledge and general curiosity about anything related to Greek Mythology.
But besides all that, the homie Brian Crecente at Kotaku posted six video clips by the creators of God of War. Each part touches on different aspects of the game like the general story line, The Gods, The Titans, The Creatures, The Heros, and Kratos' ultimate fate. I'm not very sure if this is on the DVD that came packaged with God of War II because I haven't even touched the DVD or taken the game out of my PS2 since I bought the game last month.
Anyway, I can't put the video here, but you can check them out here on Kotaku. (Very worthwhile and interesting)