Dude, what is wrong with Orion? Seriously, he's like that kid in school who just can't stay out of trouble. You know the kind we're talking about, right? The teacher gives them chance after chance, but they just can't seem to help themselves. They always do something to land themselves in the principal's office.
Orion was totally like one of these troubled kids... no doubt. Even though he's got tons of potential. You know: best hunter ever, walks on water... he just can't seem to help bringing himself down. His commits his first major crime when he gets drunk and forces himself on Merope. Her father, King Oinopion, blinds Orion as punishment, but he still doesn't seem to learn his lesson. After his sight is restored by Helios, Orion comes back to take revenge on the King. (Seriously, Orion? You think the King is the one who needs punishment here?)
Later on, the big guy seems to have turned over a new leaf. He's hanging out with a better crowd: Artemis, whom he hunts with all the time. Next thing you know, though, Orion gets all big headed, and brags that he's going to kill every wild animal on earth. Sure, Gaia might be pretty harsh when she sends a scorpion to kill him, but there's no doubt that once again Orion has brought about his own downfall. Oh, Orion, how can a guy who can walk on water have sunk so low?
You'll find a gigantic pile of info on the giant Orion here.