With their powers, it didn't take long to reach Master Fu's. They landed on the rooftop together, their movements synchronized from so long working together. Both dropped their transformation as they entered the staircase from the rooftop door.

They descended the stairs in silence. Marinette was still getting used to the feeling of walking next to Cat Noir not in costume, especially considering it was Adrien, and with all the emotional turmoil he had put her through recently. She just wasn't ready yet to converse with him in a casual manner.

She knocked on the door to Master Fu's and it swung open almost immediately. The diminutive form of the last guardian of the miraculous stood before them, looking surprised at first, but then his expression turned hard.

"Come in," he said simply, ushering them into the room and shutting the door behind. They had both been here before, in times of need, but never together.

"I see you are together," Master Fu said gravely, his expression disapproving, as he turned to address them.

"What! No," Marinette began to stammer, "We're not together! That's not- Of course we're not- I mean…" She stopped when she noticed both Master Fu and Adrien were giving her looks, as well as the three kwamis that now hovered about the room. Her shoulders drooped and she fell silent.

"There is good reason for you to keep your identities a secret," Master Fu went on, ignoring the outburst, "yet I see you no longer keep them."

"It was my fault, master," Adrien sighed, "I was reckless and… lost my miraculous during the fight, so Marinette found out."

"I see," Master Fu nodded thoughtfully, "I suppose there's nothing to be done about it now. Now tell me what brings you here."

"Master," Adrien stepped forward, "Is it possible for a miraculous to… hurt it's user?"

"Hurt?" Master Fu looked surprised, "What do you mean?"

"Can someone get sick from using a miraculous?" Adrien explained.

"Hmm," Master Fu stroked his beard, looking thoughtful. He began muttering to himself as his gaze seemed to drift, looking at nothing in particular. "I've never heard of such a thing," he said finally, focusing on them again, "but I suppose it's possible. Perhaps if the miraculous were damaged, then using it could cause harm to the user."

"Damaged?" Marinette finally spoke up, "But I thought you said the miraculous are indestructible?"

"What?" Master Fu blinked in surprise, "I never said that."

"B-but you told me…" Marinette trailed off, trying to remember what he had actually said.

"No, no," Master Fu corrected her, "I said they are nearly indestructible. The magic that was used to create them also protects them from most harm, like the magic of your suits, but a sufficient amount of force would be able to damage one or, perhaps, even destroy it."

"So if the peacock miraculous were damaged," Adrien reasoned, "the user could get sicker and sicker every time they used it?"

"It is possible, yes," Master Fu agreed, though he didn't sound too certain, "Why do you ask these questions? Is there something I should know?"

"Yeah," Adrien sighed. Marinette could see again the pain in his eyes, that feeling of betrayal as he worried that someone close to him could be his nemesis. "Nathalie, my father's assistant, recently got sick," he explained, his voice soft and his eyes downcast, "It was on Heroes' Day. Then she got sicker, twice, both times right after Mayura appeared again."

"I see," Master Fu said thoughtfully, his expression grave. A brief silence prevailed between them as he seemed to digest this information, considering what to do with it. Finally, he spoke up again, "I know this is difficult for you, Adrien," Master Fu spoke with fatherly compassion, "but this must be investigated. You accepted the mantle of Cat Noir, and now you must do what you can to protect the city. That is your first priority."

"I… know," Adrien answered slowly. Taking a deep breath, he seemed to steel himself, a look of determination coming to his eyes. "I'll do whatever it takes."

Marinette was never more impressed with Adrien than she was at that moment, shoving aside his own interests and preparing himself to do what had to be done. Still, despite the brave face he put on, Marinette could see the sadness in his eyes, the regret as he seemed to watch the world around him grow dark.