In a more dangerous situation, perhaps they are all in a magical battle, and Ron, being hot - headed, makes a mistake that puts Hermione in jeopardy. Draco, who has been working on his own path of redemption in the fanfiction, uses his magic skills to save Hermione from the danger Ron's mistake created. He might then give Ron a scathing look as if to say 'You should be more careful with her.'
One possible scenario could be that Ron says something really mean to Hermione during an argument, and Draco, who has secretly been observing Hermione's intelligence and kindness, steps in to defend her. Maybe he uses his quick wit to shut Ron down verbally.
One possible motivation could be that Draco has changed. He might have seen the error of his ways and decided to do the right thing. Another motivation could be that he has feelings for Hermione, even if they are not fully realized yet. He doesn't want to see her in a bad situation, so he steps in.
Draco might be motivated by jealousy. He could be jealous of Ron and Hermione's friendship or a possible romantic relationship between them. So he tries to harm Hermione out of spite.
Well, in some versions, Ron might use his quick wit and knowledge of Hogwarts' secret passages to outmaneuver Draco. He could lead Hermione to safety through a passage that Draco doesn't know about.
One possible reason could be that Draco has had a change of heart. Maybe he realizes that Hermione is a person worthy of protection regardless of her House or her friendship with Ron. He might have seen some injustice about to befall her from Ron and his Gryffindor bravado getting out of hand.
One scenario could be that Draco witnesses Hermione being bullied by some Death Eater - sympathizing students. He steps in and uses his quick wit and knowledge of magic to outsmart them. Another could be in a situation where Hermione is being wrongly accused of a crime and is facing abuse in the form of unjust imprisonment. Draco, having some influence in the Ministry due to his family, intervenes and clears her name.
It could be that Ron starts dating another girl in the fanfiction, and Hermione has feelings for him. Seeing him with someone else would be heart - breaking for her and cause her to cry.
One possible scenario is that Snape steps in during a confrontation. Bellatrix is about to harm Hermione, and Snape, using his quick reflexes and advanced magic, stops her. He could be acting out of his own sense of right and wrong, or perhaps because he has a hidden agenda that involves keeping Hermione safe.
One possible plot could be that Ron is under the influence of a dark spell that makes him act aggressively towards Hermione. Severus, being observant, notices this and steps in to protect Hermione. He uses his potions knowledge to create an antidote for the spell on Ron.
Well, it could completely shift the relationships in the story. Instead of Hermione being in a difficult situation with Ron, she now has an unexpected ally in Draco. This might lead to a new friendship or even a different kind of relationship between them. It could also make Ron realize his mistakes if he was indeed being abusive in the fanfiction.
Over time, if the fanfiction progresses, Hermione could become a sort of bridge between Ron and Draco. She might encourage them to get along, now that Draco has shown that he can be on Hermione's side. Draco might also start to see Ron in a different way, realizing that Ron's jealousy or rudeness towards Hermione was born out of his own insecurities. This could potentially lead to a more complex and interesting dynamic between the three of them.