Sina isn't really used to cats the way they're kept around Skyhold-- her clan has no need for them, as they rarely stay in one place long enough for vermin to become a problem. But she'd been somewhat adopted by Buttercup when he was around, so when Purrelden hops up beside her, she actually stirs and timidly holds out a hand to her.
She doesn't answer Anders right away, still collecting herself as she lightly pets the cat. If she turns toward him, he'll see how weak she is.