He could be very empathetic. Naruto has been through a lot himself, and he would understand if Anko is drinking because of some past traumas or current stress. So he would listen to her if she starts to ramble and offer words of encouragement.
Naruto might be a bit shocked at first, seeing the usually tough Anko in a vulnerable, drunk state. He would probably try to help her, like getting her some water or finding a place for her to rest.
If Naruto does figure it out, he could be really flattered. He might see Anko in a whole new light. But he would also be a bit confused because he has always seen her more as a senior or a friend. He would probably try to handle the situation gently, not wanting to hurt her feelings.
Naruto would probably be extremely hurt at first. He values friendship and loyalty a great deal, so Anko's betrayal would be a huge blow. But he wouldn't give up. He'd likely try to talk to Anko to find out why she did it, hoping to change her mind.
Sakura might be initially shocked and a bit jealous, but she would probably come around to support Naruto as a friend. Kakashi would be more of a calm and collected figure, offering advice on how to handle the situation both as a ninja and as an expecting father. Sasuke, on the other hand, might be indifferent at first but later show some concern for Naruto's well - being in this new situation.
Perhaps in the fanfiction, a drunk Anko challenges Naruto to a friendly spar. Naruto, not wanting to take advantage of her drunken state at first, tries to decline. But Anko insists, and during the spar, Naruto has to be extra careful not to accidentally hurt her. In the process, they both learn more about each other's fighting styles on a more personal level.
Maybe Anko would be shocked to find Naruto drunk. She could scold him for acting irresponsibly as a ninja. Or she might try to help him sober up and figure out why he got drunk in the first place.
Anko might initially be very angry. She has a prideful nature, so being humiliated by Naruto would make her want to lash out. She could challenge Naruto to a rematch immediately, vowing to make him pay for making her look bad.
I'm not sure exactly where you can find a specific 'Anko finds Naruto drunk' fanfiction. Fanfiction can be scattered across various platforms like FanFiction.net, Archive of Our Own (AO3), and Wattpad. You'd have to search using those keywords on these sites to see if there are any relevant stories.
In some Naruto fanfictions, Anko might be depicted as cheating on Naruto, but this is not part of the original Naruto storyline. Fanfiction allows for a lot of creative and often non - canon interpretations of characters' relationships.
Perhaps Anko is trapped in a genjutsu and Naruto uses his own experience with breaking free from illusions to save her. He could sense her distress and use his chakra to disrupt the genjutsu, freeing Anko. This would show Naruto's growth and his ability to help those in need, even a more experienced ninja like Anko.
Naruto is often full of surprises. He might first act all nonchalant and say it's just a new thing he's trying. But when he sees Anko's serious face, he would start to panic a bit. He could try to make a joke out of it, like 'Hey, Anko - san, this fanfiction - drink is supposed to make me write better ninja stories!'. In the end, if Anko doesn't buy his story, he would probably just bow his head and admit it was a stupid idea.