The whole Fairy Tail guild could catch them. Maybe they are having a big celebration at the guild hall and Natsu and Lucy are in a corner, sharing a private moment. And then suddenly everyone notices and there's a big uproar of laughter and teasing.
Perhaps in this fanfiction, they are caught in the middle of a magical experiment gone wrong. Natsu's fire magic combined with Lucy's celestial magic creates a big commotion and their guild mates catch them in the chaos. This could lead to some humorous moments as their friends try to figure out what happened.
It could be one of their friends like Leo. He's always so curious and into other people's business. He might accidentally stumble upon them while looking for some new mechanical parts in a secluded area where Percabeth thought they were alone.
Well, it could be about Nalu having an argument over a lemon. Maybe Nalu found a lemon tree and one of them wants to use the lemons for cooking while the other wants to make lemonade. So they get angry with each other over this silly lemon - related thing.
There's also a chance that Dumbledore gets caught by a group of rogue magical creatures. For instance, if he was exploring an area that was supposed to be off - limits to wizards and the creatures there saw him as an intruder. They might not be as rational as wizards and could hold him captive without really understanding who he is.
Even some of the Hogwarts professors or students could catch Dumbledore. Maybe a curious student stumbles upon Dumbledore in a restricted area where he's doing something strange. Or a professor who has a different view on how to run the school catches Dumbledore in the middle of an action that they think is wrong for the school's environment.
Maybe it's a strict teacher or mentor in their world. If they are breaking some rules, like skipping important training or lessons, the teacher or mentor could catch them. This would then lead to some form of punishment or a lecture about responsibility in the 'nico and will get caught fanfiction'.
Obviously, Nalu is the main focus. There could be other characters as well, like their friends who might try to calm them down during their angry lemon - related spat. But Nalu is definitely the central characters in this fanfiction.
You can try fanfiction websites like FanFiction.net or Archive of Our Own. Just search for 'nalu dragon lemon' in their search bars. There might be a lot of works there.
It could be Chiron, the centaur. He's always keeping an eye on the campers and would likely be concerned if he caught them up to something. He might give them a stern talking - to and some extra chores as punishment.
The 'hot' aspect usually implies some passionate or romantic moments between them. It could be a steamy kiss or a heartfelt confession. In terms of the 'lemon' part, it might be incorporated in the setting, like they meet at a lemon grove or something related to lemon is a key element in the story. This adds a unique flavor to the fanfiction.