I *heart*
Felix. It has such a great meaning. I like
Leo, but not nearly as much as
Felix and I prefer
Leo as a nn for
Leonidas.
Felix and
Scarlett would be a beyond awesome sibset,
Scarlett and
Leo sound good too but not nearly as "Wow". Also,
Scarlett and
Leo make me think of the celebrity
Scarlett &
Leo, which wouldn't be a deal-breaker for me if I loved the name but its something to keep in mind.
Felix John also sounds better as a combo,
Leo John is rather choppy.
Why not take both names to the hospital and decide when you are holding him? Good luck, and keep us posted :)