It was summer, so why did Finn come out of his room instead of staying there until summer was over?
He didn't want Luca to get suspicious of him. It was definitely not normal for someone to stay in their room for days. Luca might think he was hiding something, and it was about time the black-haired man lost his patience and came to him to question him directly.
That was why he decided to come out of his room today before the younger man felt more suspicious of him. It just so happened that he had returned to his normal human form today, and that was why he took the gamble of coming out of his room.
He ignored the fact that he had no control over his transformation at all, and he also chose not to care about how he might randomly turn into a zombie while he was out of his room. He just wanted to appear normal in front of Luca, not expecting that it would be the second possibility that would happen tonight.
