In this kind of fanfiction, perhaps Harry discovers some serious misdeeds by Snape that lead to his dismissal. For example, Snape might be caught unfairly favoring Slytherin students in a major way, like giving them unearned high marks in exams while unduly punishing Gryffindors. Harry, being the observant and just character he is, would report this to the proper authorities at Hogwarts, which could be Dumbledore or the school board. And this could start the process of Snape getting fired.
Hermione could be a great help. She is very intelligent and resourceful. She could help Harry find evidence against Snape. For instance, if Snape is suspected of cheating in grading, Hermione could use her knowledge of Hogwarts' grading system and records to dig up proof.
For Harry Potter, it could be a mix of emotions. On one hand, he might be relieved as Snape has been tough on him. But on the other hand, he might also feel a bit guilty or confused, especially if he later discovers that Snape was wrongly fired. Hermione would probably be outraged at the injustice of it all and might try to find evidence to get Snape reinstated.
On the other hand, Harry could be proud of himself for standing up for what he believes in. He may think that he has made Hogwarts a better place by getting rid of a teacher who was not treating students fairly. But at the same time, he might have mixed emotions as Snape was also an important part of the Hogwarts environment for so long.
It could be his immediate superior. If his superior was jealous of Lloyd's intelligence or was under pressure from higher - ups to show some results, he might have used a minor mistake of Lloyd's as an excuse to fire him.
Well, in a fanfiction, SpongeBob could be fired due to a misunderstanding. For example, Mr. Krabs misinterprets something SpongeBob says as a threat to quit. SpongeBob is devastated. He then tries different jobs like being a delivery boy for a seaweed company. However, he misses the Krusty Krab so much. In the end, Mr. Krabs figures out the truth and welcomes SpongeBob back with open arms.
One possible plot could be that due to some false accusations of improper teaching methods, Aizawa gets fired. His students then band together to prove his innocence. They collect evidence of his effective teaching, like how he has helped them improve their quirks and grow as heroes in training. Eventually, they manage to clear his name and he is reinstated.
One great Severus Snape fired fanfiction could be 'The Aftermath of Snape's Dismissal'. It might explore how Snape copes with being fired from Hogwarts. He could be forced to find new allies in the wizarding world outside of the school. Another could be 'Snape's New Beginning' which delves into his journey to redeem himself after the unjust firing.
Well, it could be that Harry discovers some major misdeeds by Fudge. Maybe Fudge has been covering up dark magic activities within the Ministry. Harry then finds evidence and presents it to the proper authorities, leading to Fudge's dismissal.