Coulson doesn't know what to expect when he sees Skye coming towards him. The tears on her cheeks may have been dried and wiped away, but her eyes are still red and she's sniffling slightly.
Maybe he'll get a slap, for not telling her everything as he discovered it, for waiting until now to reveal the truth to her.
Maybe she'll fall apart again.
He really doesn't know what to expect, and that's what he likes and hates about Skye, her unpredictability.
Instead she gives him a brave smile and tells him thank you for telling her that she's had a family all along and he's never been so proud in his life.