The truth was: people did not like Potter, Weasley, and Granger coming to work for the Ministry. Powerless people felt it was a breach of trust to have their heroes suddenly side with the government. And those in power resented a bunch of upstarts coming in on the coattails of that rebellious replacement, Shacklebolt. They gave the trio impossible tasks in order to stay on, all the better to fire them when they inevitably failed. Potter was told that he would have to solve the decades-old murder of Tiberius Ogden’s cousin, with his only clue a photo in the Prophet. All the other evidence had mysteriously vanished along with the body. Potter winced, went to work, spent a week furious and bored out of his mind in the newspaper offices, and, miraculously, cracked the case (Wilkie Twycross did it. And, as they say in the MLE, he would have Apparated away with it, too).
They also tried to remove Granger. They sat her at a desk and kept a snowy owl’s vigilant watch on her. They told her not to leave until she had tracked down the Department of Mysteries’s missing collection of flying and teleporting seven-league boots (overkill, but that was the Department of Mysteries for you), which they claimed had been absconded with by some fashion-conscious Voldemort supporter. The truth was, every last boot had gone up in Fiendfyre during the war and they all knew it, but the paperwork documenting this was conveniently missing. Granger sifted through reports all day, and then, finally, sent off a missive through the floo. They left her working through the night, and rejoiced to find her desk empty in the morning. But at half past she floated in, well-rested, and said, “Oh, is this what you were looking for?”
The easiest to oust should have been be Weasley. He was the weakest link, in their opinion; they knew all about his rigid mother and his bumbling father and his upbringing, and they suspected that they could have a bit of fun with it, they could make him squirm in the process. So they told him he would be doing a routine patrol of Knockturn, and of course he would be fired if he couldn’t clean the place up, but not to worry: it was routine, and this was positively the easiest stretch of Knockturn, just a few smuggling rings and a dragonsblood dope den, no trouble at all. Perfect for a beginner. And then they deliberately assigned to him the worst route, the fool’s route, that long stretch with all the houses of lewd foreign monster girls. When he appeared the next day, bleary-eyed and somewhat horrified-looking, they pounced on him and said, “We notice it’s just as bad as it was before, Weasley!”
Weasley blinked at them. “Not at all,” he said. “It’s a cleaner place now. Go and see. Why, even my old mum would approve.” They did go and see. It was, to his credit, a cleaner place. The placards did the trick. His old mum would have approved.
So the miraculous trio stayed on. They could not be ousted. They seemed unstoppable. No one knew how they had done it.
Except for Ms. Lovegood, whose father had snuck into the Prophet offices years ago and seized up copies of all their lost work on the Ogden case. And Winky the house-elf, who had access to the Hogwarts time turners and was fully capable of defending against fire. And Fleur Delacour, who spoke the language of the Veela and could provide helpful pointers on how not to inadvertently proposition them.
She’d also laughed herself silly when she’d received Weasley’s Owl.
Potter later reformed the Prophet and gave a boost to the Quibbler’s public image. Granger championed the cause of house-elves everywhere and made sure their Fiendfyre-repelling methods went public, with full credit to the elves themselves. And Weasley became a passionate magical creatures immigration advocate (and, thanks to some research Hermione forced onto him after the Knockturn Alley affair, a fierce protector of the rights of the working girl — or fellow).
Heroism at its finest is not an individual endeavor. Sometimes one cannot win on one’s own. A true hero recognizes this. And, if they end up taking all the glory, they still find a way to pay it back, somehow.