Luna crossed the border into Rion's territory first over Amond's. But he is smart enough to learn to blend in eventually. I originally wanted his introduction to bring purple into Eleos' world; but that had to change due to future character considerations.
Luna instead learns the culture and blends in when he visits new places. So he picked some reds and blacks to blend in with the populace there. So his color page consists mostly of reds picked off his color scheme and vines mixing Eleos and Luna together finally.