Some characters might be amused. For example, Sans would probably make some witty remarks about the fanfiction's plot twists. Papyrus, on the other hand, might be a bit confused at first but then get really excited if he finds a heroic role for himself in the fanfiction.
Honestly, 'y f n' in fanfic could be a random combination of letters without a widely recognized meaning. Maybe it's a made-up term by the author for a special plot element or character trait.
One common theme is probably the healing process. Since there's the 'hurt y n' part, often the BTS members will be involved in helping the character heal from whatever has hurt them.
I'm not entirely sure specifically what that particular 'bts y n is a hybrid hurt fanfiction' is about without more context. It could be a fan - created story that involves the BTS members, some kind of 'y n' (which might be a made - up or specific character in the fanfic world), and it's a 'hybrid' concept which could mean a mix of different elements like human and something else, perhaps supernatural, and 'hurt' might imply there are elements of pain or emotional distress in the story.
Well, it's a bit difficult to just recommend one off the top of my head. However, when you're exploring these fanfictions, look for ones that have well - developed characters. In a 'bts meets hurt y n' scenario, the way the characters interact and how the story unfolds around their meeting and the 'hurt' aspect can really make or break the fanfiction. It should have a good balance between the relationship building, the pain or hurt element, and the overall plot progression.
It can change the whole mood of the story. If Y N gets hurt, it might introduce a sense of urgency and concern into what was previously a happy and exciting concert - going experience.