I'm not sure. Maybe some parts could be true, but without proper investigation and cross-reference, it's difficult to give a definite answer. There could be exaggerations or misunderstandings.
Well, in some versions, Fred might use his quick-witted magic skills. He could cast a distraction spell to draw Bellatrix's attention away from Hermione. Maybe a spell that creates multiple illusions of himself, confusing Bellatrix long enough for him to grab Hermione and disapparate them to safety.
Well, Kevin from The Office could tell a story like this. There was a time when there was a big client coming to visit. Kevin was asked to clean up his desk area which was always a mess. He tried to hide all his junk in the drawers. But as he was doing so, he accidentally knocked over a cup of coffee all over some important papers. He then had to quickly dry them off and make it look presentable. When the client arrived, they actually complimented on how 'homely' the office looked because of Kevin's little mess.
Hermione, on the other hand, could become more daring. She is already brave, but this situation could push her to take risks she normally wouldn't. She might be the one to suggest trying untested spells or taking paths that are less known in order to escape. As they run, she could learn to trust her instincts more and not just rely on book knowledge.
Their relationship would likely become more serious and responsible. They'd have to put aside some of their youthful antics as they now have a child to think about, even if it's from the future. There would be a new level of trust and understanding as they work together to deal with the situation.
In the fanfiction, it could be that Ron is consumed by jealousy or a false belief. This causes him to lash out at Hermione in a way that endangers her. Fred, having a protective streak, especially towards his friends, jumps into action. He might engage Ron in a duel of sorts, not with the intention to harm but to subdue him long enough to break whatever spell or negative emotion has a hold on Ron and thus save Hermione.
Well, in this fanfiction, it might be that Ron has been misled by a malicious wizard who has poisoned his mind against Hermione. Fred, being observant, realizes what's going on. He uses his charm and wits to first distract Ron and then casts a spell to free Ron from the mind - control, all while protecting Hermione from Ron's erratic behavior.
In a fanfic where Fred is sick, it might start with him collapsing during a Quidditch match. Everyone is shocked. The Weasley family rushes to his side. Ginny is especially distraught. They take him to St. Mungo's, and there they discover it's a very rare wizarding disease that is passed down through certain wizarding bloodlines. The Weasleys start to recall if there's any history of such an illness in their family. While Fred is in the hospital, he has strange dreams about the Marauders and their time at Hogwarts, which might give him some clues on how to get better.
Hogwarts: Weasley Is Our King was a recommended novel, which included supporting actors Fred Weasley and George Weasley. This book can be read on Qidian Chinese website.
There's not enough information given to really know who Kevin Will is in the 'end of watch the kevin will story'. He could be anyone. He might be a character in a fictional story, in which case his identity could be shaped by the plot. For instance, if it's a mystery story set around a night watch, he could be the detective or the person who holds the key to solving the mystery. Or if it's a more personal story, he could be someone going through a life - changing experience during his watch. But all of this is pure speculation at this point.