Thanks for your answer.
My idea got delivered with an element of surprise!
I wanted to suggest that Octavia Blake gets secret injected with nightblood (secret to the audience AND to herself) - simple to be able to take the flame anytime - this to add her name in the "line of heda's" where it belongs!
Mainly to save ALL 12 clans, establish Wonkru and bring them back to the surface.
As we all know now - Echo got the nightblood and also Echo keeps on the violent path with fighting - while Octavia found her way out of the dark.