Star Trek: Discovery 1x08 "Si Vis Pacem, Para Bellum" has a bizarre scene that I can't make sense of. L’Rell tells Admiral Cornwell that she wishes to defect, and they make their way through the hallways to the ship. Then this happens:
[Some Klingons spot them in the halls and confront them]
L'Rell: You're not what I expected.
Admiral Cornwell: Neither are you. [Grabs L'Rell's knife]
The two then fight, with L'Rell apparently killing Cornwell, then telling the other Klingons that she was going after the escaped prisoner.
I don't understand what the meaning of these words were. What did L'Rell mean when she said "You're not what I expected". That sounds like the words one would say when they realize they've been betrayed, but that's obviously not what either of them did, since neither summoned the Klingons.
What is the meaning behind the words in this scene?