It doesn't take a genius to notice that Delphine, when pushed, reverts to French. Luckily, Cosima's a genius anyway.
Leekie promised treatment, which ought to capture her whole attention. Experimental, stem-cell based treatment, behind Rachel's back. But Delphine is angry in a way Cosima's never seen. She is stiff with rage, a stream of invectives half breathed into the world pouring out of her in clipped, angry French. If she had doubted Delphine before, she cannot now.
They leave the office together, Delphine's hand finding Cosima's as they do and squeezing tight. Their lab is close; they don't speak until they're inside.
"Cosima, I-I didn't know, I am so, so, so frustrated and angry-" Cosima looks at her, and she falters. Her head falls. She pushes her hair back from her face. "Merde. Putain de merde. Cosima-"
The kiss is meant to be sweet but doesn't quite make it, lost somewhere around hungry and desperate "Hey. I know you didn't know," Cosima breathes against her mouth before she is entirely distracted by Delphine's tongue. "I trust you." It's not the whole truth, but it's close enough.
"Merde," Delphine whispers back, smiling into the kiss. "I didn't think I would hear that."
"Planning on taking advantage, Dr. Cormier?" Cosima slips backwards out of her arms to sit on the couch, eyebrows raised and smile positively toothy.
"Je veux tu baise. Je vais te baiser. Tu voudrais, non? Je comprends qu'il. Je te comprends." She kneels as she speaks, fitting into the space between Cosima's knees and waiting for her to lean in before kissing her. It doesn't take a genius, but there are better ways than anger to push Delphine into French.