Their eyes locked, and then it wasn't uncertainty that kept him frozen in place, it was fear. Severus had so many things to tell her, and yet at the same time, nothing at all. Nothing that she wanted to hear, at least. Everything he had to tell her, besides repeated apologies, would be bad news to her. Lily might have been from 1977, making her Lily Evans, and not Lily Potter, but she would surely wouldn't appreciate hearing anything about him any more than she would have after she married Potter.
When she looked away, he wondered what emotion was behind the action, and very nearly asked her, but he didn't have the right anymore, so he stood there in silence, trying with all his might to think of something he could say to her. There wasn't much. She was as beautiful as ever, a little younger than he remembered, and without that pesky ring around her finger, for which he was glad. But it wouldn't be Potter that stood between them and their friendship, it would be his own stupid mistakes.
"You're from 1977, you said?" knowing very well that was what she had written in her journal.