Leliana figures it out first, quite possibly even before Josephine does—and definitely before Cassandra does, but then, Cassandra can be very selectively dense. Certainly she figures it out well before either of them says anything to the other. She is, barely, tactful enough to wait for the copper to drop before she says:
"So, you and Cassandra?"
Josephine doesn’t even pretend to be surprised. There is a light in her eyes that makes Leliana very happy, despite herself. “She’s sort of marvelous, isn’t she? I’m not sure the best way to approach her, though; it’s possible she might be easily scared off. Still considering.”
"Josie, she yells and hits things with a sword, that is her main competency." Leliana doesn’t miss the way that makes Josephine smile, of all things. Maker, this is hopeless. “You could do better, you know.”
Josephine almost never directly contradicts anyone. It is part of her genius as a diplomat that she never has to; she talks, sweetly, and talks, and talks more, and you find yourself suggesting the very thing she wanted in the first place, so that she only has to smile and agree with you. It is a testament to their relationship that Josephine says, “No.” She smiles and bites her thumbnail. Hopeless, hopeless, hopeless. Somehow that only makes Leliana happier. “No,” Josephine says again, “I really don’t think I could.”
"So," Leliana says, "You and Josephine."
Cassandra’s stony face goes even stonier. Sometimes she puts Leliana in mind of Shale. “I don’t know what you’re talking about.”
A glare from Cassandra is enough to terrify most people into submission. Leliana is pleased to be in the select club of people who are not all that impressed by it. “I only say something because she is dear to me.”
"I don’t. Know what. You. Are. Talking. About.”
"All right, all right, if that’s how you want to play it." Leliana waves a hand. "But do know that I do not look kindly on people who hurt her."
Cassandra’s infamous eyebrows come down in a glower. “If anyone hurts her, they will answer to me and my sword first,” she says, apparently unaware that she has utterly given lie to her ‘don’t know what you’re talking about’ of three seconds ago.
But Leliana doesn’t point this out. She laughs. She laughs, and the feeling that spreads its wings inside her heart has a name: relief.