I think [name_u]Orion[/name_u] should work, depending on the education level where you live. In any case, I don’t think [name_m]Sebastian[/name_m] is terribly common. I picked [name_u]Orion[/name_u] [name_m]Sebastian[/name_m], though the similarity of the endings bothered me a bit. [name_u]Orion[/name_u] [name_u]Alexios[/name_u]?
I gave a vote each to both [name_u]Orion[/name_u] [name_m]Augustine[/name_m] & [name_m]Milo[/name_m] [name_m]Augustine[/name_m]. Interestingly, I’m not usually a big fan of [name_m]Augustine[/name_m], but with [name_u]Orion[/name_u] & [name_m]Milo[/name_m] it works beautifully, and I find myself liking it.