A plotline could involve Anko being assigned to train Naruto in some special jutsu or skill. As they spend time together in training, they grow closer. However, Anko is worried about how others will view their relationship, especially the older and more traditional ninja. Naruto, on the other hand, is concerned about how it will affect his goal of becoming Hokage. So they keep their love a secret. They might have to sneak around, meet in secret places, and communicate in coded ways to avoid detection. This could lead to a lot of tense and exciting moments in the fanfiction as they try to balance their relationship and their duties.
One possible plotline could be that they start as friends who gradually develop feelings for each other. But due to Anko's past or Naruto's status as a Jinchuriki, they decide to keep it a secret. Another could be that they are thrown together on a mission and during that time, they discover their love for each other but fear the reaction of others, especially Tsunade, so they keep it under wraps.