i dislike how certain parts of the fandom mischaracterize the marauders characters completely and write them without any depth to their personalities, only depicting them as onesided and without nuance. no, james potter is not completely a golden boy, while he is a good person yes, who sacrificed himself at 21 for a good cause, barely out of school, he canonically sexually assaulted severus snape when they were teenagers, and bullied and ridiculed him for years on end. you can write him as having a good heart while also acknowledging his faults. its why as much as i absolutely adore tcoptp, james' characterization in it isn't my favorite; i dont feel like he's depicted as mean enough. however, since the story is told from remus' point of view its understandable that he might see james as better as he really is, but that's a tad bit off topic.
as well as this, i find it contradictory when writers depict snape as someone who is completely bad or completely good. he grew up poor and in an abusive household, as well as being bullied by the marauders during his teenage years: the years long buildup of humiliation and feeling of never really belonging, whether it be at home or in school, is understandable to me why he eventually joined the death eaters, finding solace in a fellow group of outcasts that made him feel like he was accepted for once. im not saying him joining a group of fascist, xenophobic, pureblooded-supremacists is okay. im just saying that i get why he did it.
as for severus' adult years, bullying the son of your dead rival and dead crush for something that happened in your teenage years is incredibly petty. while i do acknowledge that what he went through had to be incredibly influential on his mental health, enough to the point where he continues to hold a grudge over, years long after his school years, snape is an adult and he should know better, regardless of what he experienced. the bullying and his abusive childhood does not justify the childish and biased way he belittles and behaves towards harry potter. as the person with more experience in this situation, he should have the maturity to at the very least not take out his anger on an adolescent who has done nothing against him.
while one might say, "oh but he redeemed himself cause secretly he spied for dumbledore as well as posing as a follower of voldemort, always tries to protect harry no matter how rudely he treats him, dies for the war, b/c of this he never did anything wrong! he isn't a bad guy," etc., etc., that does not erase the fact that snape still bullied harry potter through his years at hogwarts- and if you want to get more canonical, he does not even forgive nor take accountability for his mistreatment towards the boy.
"yeah but harry forgives him anyway and even names one of his children after snape to honor him", yes, while that does happen, that is nevertheless harry's choice and does not resolve snape's flaws. you can't paint severus snape as someone who is either completely evil or completely good without acknowledging both his flaws and his positive traits.
these are only two examples of mischaracterization that i see in the marauders fandom, even though there are definitely more out there, as all fandoms have. to summarize: characters, and people are more complex than the simple black and white, rather their personalities are shades of grey. in the words of sirius black, harry potter and the order of the phoenix, movie 5, "...Besides, the world isn't split into good people and Death Eaters. We've all got both light and dark inside us. What matters is the part we choose to act on. That's who we really are."