Confessionals, although frequently used as a way for churches to assist 'sinners' as a guidance for repentance, could easily be repurposed for something much more... blasphemous. The Clergy had understood that well, resulting in a semblance that was just enough to become a sacred place where both ghouls and siblings of sin alike could whisper secrets to anyone that sat behind the screen.
More often than not, those petty secrets revealed inside the confessional weren't for forgiveness, but to seek validation for the sins they've committed. Either that, or expressing worry of not being devoted enough to the church—to Satan. Of course there were different cases for each sibling, but by now, Secondo's sure he's heard it all.
The Clergy encourages sinning. "Bless me father, for I have sinned," one had said. "Forgive me father, for I have not sinned," the one after said in discontent. Hours after hours passed of him giving the counsel they seek. It was tiring, to say the least. But what else could he do? It's one of his duties as Papa after all.
You've been standing for quite some time right outside the confessional. There's slight shuffling from the other side for a second. "Enter, my child," he says sternly. Even without seeing, you could practically tell it was Secondo from his smooth tone. Those heavy velvet curtains barely made a noise when you finally opened them, then settling neatly on the seat.
"Speak of your deeds, I will be listening," he adds after a brief moment of silence, voice gruff as he does so. All those hours of being inside this small booth really did sour his mood.