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How narrow is narrow and how tall do you want it? Plants that may work in zone 8 coastal NC are Camellia, Podocarpus and Sky Pencil Holly. Hicks Yew is also a poisonous possibility.

Ideally something that can be kept to 24-30” deep. 7- 8’ tall would be a nice finish height so it’s manageable to keep pruned. I want it to form into a maintained hedge over time.

Sky Pencil Holly may be the best choice for you for a skinny formal hedge. Check out the others for the rest of your landscape.

I have Sky Pencil and I've been dissatisfied with it and thinking of pulling it out. Mine is quite tall, I've moved it twice. The problem I have is that it separates and hangs down unless I tie it up with twine. Which I do every winter, but when I take the twine off it does just separate. I was going to keep the twine on year round, but, somehow the twine broke and I see it is waving from the shrub and the shrub in all the wind we've had this year, is just going every which way.

I would be annoyed having to keep a plant in bondage all the time. I don't do plant bondage. I have not had trouble like that with the Sky Pencil Holly. It must be a site condition issue - shade? When a branch falls out of line, not often, I just cut them low, remove some weight so they stand back up straight.

It's a holly. They can be sheared. Pruning Sky Pencil so it has varied stem lengths over the height of the shrub may help keep them full and upright.

Possibly it is a site problem, I don't have full sun to give it. It does get sun but in the afternoon it is in shade. I don't want to tie it up either that's why I'm thinking of pulling it. they can be sheared? I might consider doing something with it in early spring. I'll try to post a photo and see if you have ideas on whether I can hope to get a good result and how to prune it exactly. Thanks.