Clarke manipulating Nia was so brilliant. Ensuring the safety of her people and then, putting in just the right amount of selfishness/self-concern — “and me?” though we know that if it was real, Clarke wouldn’t have even thought about herself — that it would be believable, plus speaking Trigedasleng and insisting on a blood oath (which would be necessary for poisoning, but the Trig talking made it more credible). And Nia fell for it because how wouldn’t she? It was perfect. Only Ontari was distanced enough to see through Clarke’s guise (and I’m glad she did, because murdering Nia would’ve only brought more conflict).
I don’t know how anyone can say that Lexa manipulates Clarke, when Clarke is the master of manipulation. No one can fool her. She fools everyone else.