I remember a long time ago Riot said they were pumping out new champions just about every patch because they wanted each geographic region of Runeterra to have their own take on each role, but if this is the case then why is there no support champion for Noxus? I mean, it's not like the idea of a support would be completely alien to Noxus. You could make a vanguard character like Leona and it would still fit perfectly with the flavor of Noxus. I know that it's technically possible to play Swain or Leblanc (even Darius) as a support, but they tend to do so terribly in these roles that it's never worth it to play them off meta.
EDIT: I know Sion also exists as a potential support and has seen success in the past, but it just doesn't feel right or optimal to play him in the role with the way his W and E work.