No. BTS is a musical group mainly focused on their music career, performances, and interacting with fans in proper ways like through concerts, official fan meetings, and social media. Fanfiction is often a creation by fans independently and has no obligation to be worked on by the group.
The Teen Titans would react with a combination of fear and courage. Starfire, being from another planet, might have some knowledge about the invaders which could be useful. But she'd also be worried about her new home, Earth. Cyborg would probably be excited to take on the new technology of the aliens, seeing it as a challenge to improve his own. Raven, on the other hand, would be more cautious and try to sense any dark motives behind the invasion.
One common theme is friendship. Since it involves y n meeting members of two big groups, the stories often focus on how new friendships are formed. For example, y n might bond with a member over a shared love of music.
Stray Kids, on the other hand, would also be very concerned. Bang Chan, as the leader, would take charge. He might start asking questions to figure out what exactly happened. Felix could be bringing water or something to make Y/N feel better. Lee Know would be standing guard, making sure no further harm comes to Y/N while they are in a vulnerable state.
One possible reason could be for marketing purposes. Fanfiction has a large and dedicated following, and by working with it, they could reach a new segment of their fan base. However, this would also come with risks such as maintaining the integrity of their brand.
Y/N should have their own goals and dreams. If they're interested in becoming an Auror, that can shape their actions and decisions. Their reactions to Draco should be based on their personality. If they're a shy person, they might be more hesitant around him. And make sure their dialogue is natural. Don't make them say things that are out of character just to move the plot along. For instance, if Y/N is a studious type, they're more likely to talk about books or spells when interacting with Draco.
They might immediately stop the concert. The members would be really worried. For example, Jin could rush over to where Y N is with a concerned look on his face. He might ask the medical staff what's wrong and offer words of comfort.
Finding such specific fanfiction can be a bit tricky. You could also join some BTS fan groups on social media and ask the members if they know of any. They might be able to point you in the right direction.