Just be cool, easy going, laid back, friendly, joke everytime you get the chance and be bold. That's what I did like everytime except for Aldric's route. I suspect being bold and buffoon might not be so good for Orion's route though, but I can't really tell.
Yeah, I figured that much. But I have no idea what to do from there. I'm not given very many options. It could be that I need to choose different options at the start.
I took a look at my stat values on all my saves so far. I think I've determined that my Charisma is too low on all but one of them. The one in which I could flirt with him has 15, the rest have 13 or less. I don't know if any of the other stats are relevant. Possibly Strength, doubtful any of the others. But I also just... don't know how to increase my Charisma at all...