Severus sighed. "I suppose it is the most obvious question; we should both get used to answering it." He thought back; it really was surprisingly difficult to pinpoint a precise moment. It had all happened so gradually, so naturally.
"I think I'd say the end of January," he murmured at last, a reminiscent smile lingering from his time spent lingering among pleasant memories, "when we'd both realised that it had grown to something more than a friendship."