Alfie should have been able to move - when Julien started to turn his head Alfie could have pulled away, apologized, but just barely, accidentally kissing his jaw had been like a jolt of electricity straight through him, and he'd never felt anything like that. So he was frozen, and he couldn't move, even when Julien was obviously turning to push him away...
Except then Julien was kissing him. Actually kissing him. And Alfie had been so frozen, so still, but at that he could move again - to kiss him back, to push into that kiss, inept as he was, and try.