This is something I've talked about briefly but I wanted to go a little more in depth about is that I gave each of the side characters in CC (and beyond) a more of a personal relationship to why they in particular might dislike Scorpius Malfoy or why they might not necessarily dislike him but be unable to be friends with him.
Apparently there's a production where Polly Chapman visits a grave in the background of the graveyard scene with Albus and Harry, implying she lost family to the wizarding war. I like to imagine perhaps it was an uncle or aunt who died during the Battle of Hogwarts, something which her family blamed Draco Malfoy for since the Death-Eater's wouldn't have been at Hogwarts in the first place if it weren't for him. Nevermind that Harry, Ron and Hermione would've had to go their to retrieve horcruxes and basilisk fangs regardless, and Voldemort probably knew he was losing and was getting desperate. No, no, no. Let's blame this battle on the Malfoy's instead of accepting that it was a tragic loss no one could have predicted or prevented. It's much easier to be angry at the family that got away with it than to accept that it was random.
Karl Jenkins comes from a pureblood family, and uses squib as an insult, so it seems pretty clear to me that his family thinks they're more woke than they actually are. I like to imagine Karl's mother is Leanne Dawlish (surname is my headcanon, we're never actually given one) who was best friends with Katie Bell and watched her get cursed by Draco's necklace. This to me, would mean that rather than facing their own flaws and acknowledging their own bigotry, they look at the Malfoy's and say "we're not as bad as them, us being vocally anti-Malfoy is a show of what good purebloods we are". Because why would you accept that you're flawed in a similar way to the fascists when you can just talk about how much worse they are?
Yann Fredericks has a French first name, so I like to think his family has some ancestral beef with the Malfoy's that they've completely forgotten about because the Malfoy's are simply losing track of how many enemies they made. But like, it was probably some land or inheritance disagreement or something like that where the Fredericks's got screwed over and they've held onto that grudge for like, five generations meanwhile the Malfoy's don't even remember their names. Maybe the ancestral Malfoy home belonged to the Fredericks's first. So they just hate the Malfoy's and Yann's not even entirely sure why, but his friends also do so he's just along for the ride without much personal stake in the matter.
Sophia Barclay is only a background character, but I don't think I've ever seen her in the background of the Dark Timeline, so I like to imagine she's got very impure blood. Not muggle-born, because I wanted to explore some other ideas, so I like to imagine that both of her parents were squibs. And maybe her father, I named him Douglas Barclay, came from a somewhat respectable pureblood family that was friends with the Malfoy's, but when they found out Douglas was a squib they completely cut all ties with the family and Draco was so horrible to Douglas as kids and never apologised for it, so he's got a minor grudge, but not enough that he'd put those views on Sophia. So she's weary of the Malfoy's, and that's why she's nicer to The Gang, but she's never really mean to Scorpius about it.
Craig Bowker Jr.'s father, presumably Craig Bowker Snr. having general schoolyard beef with the Malfoy's, and thinking they've gotten weak, only for Craig Jr. to turn around and say "fuck that, if you hate the Malfoy's I'm going to like them" and accidentally end up crushing on Scorpius is just so funny to me. He rebelled against his father a little too close to the sun and accidentally crushed on one of the most unavailable guys to crush on, second only to Albus Potter, and fucking died in the process. Craig Bowker Snr. hates the Malfoy's even more now.
Melody and Addison Fawley have no personal ties to the Malfoy's, but their maternal grandparents (the Padgett's) were Death-Eaters, their paternal grandparents (Marshall and Lucretia Fawley) were killed by Death-Eaters, their mother (Penelope Fawley) was cursed into a paperweight and then transfigured into a painting by a member of the Greengrass family (Gareth Greengrass), their father (Grim Fawley) then became a dark wizard who almost exposed the wizarding world to muggles as revenge against the Ministry for not finding her, after three years, they got her back, but obviously that marriage is now strained and they DO NOT want to risk being affiliated with dark magic by spending time with the rumoured child of Voldemort who just so happens to be part of the family that destroyed their parents marriage. They are staying the fuck away, even though Scorpius (and maybe Cereus Greengrass although it was literally her father that cursed Nellie Fawley) is realistically the only one who understands their pain.
Gregory Goyle fucking hates Draco now, blaming him for Vincent Crabbe's death and getting pissed off that he just gets to become a blood-traitor. What about all of the years of friendship they had? Did that mean nothing now that he was on good terms with Harry Potter? Vincent Goyle in return hates his dad, but doesn't befriend Scorpius or Albus for a long time because Gregory Goyle would fucking kill him if he found out. He just rebels in other ways because he doesn't want to be a purist but he also doesn't have a death-wish.
The Longbottom children are chill with him but don't really have much of a reason to hang out with him. Frank II's a year older, Auggie's a year younger, Alice II is friends with Sophia and Vince so on the principal of the matter she doesn't hang out with him much even though she thinks he seems like fun. They have no reason to hate him, their parents have no ill-will towards the Malfoy's, Neville and Hannah have both forgiven Draco, they just don't really have a reason to spend time with him.
Any children of Draco's old friends hate his guts, so they don't hang out with him. Any children of Harry's old friends also have a general dislike for Draco, so they don't hang out with him. Scorpius is in the very unfortunate circumstance of his family having made enemies everywhere, and the one family that don't have a reason to hate the Malfoy's have every reason to hate the Greengrass's. Quite the conundrum. And his cousin Cereus is an orphan that ends up with God knows who, because Astoria certainly doesn't get custody of her, and she unfortunately has zero contact with the rest of the Greengrass's, so Scorpius can't even befriend his own fucking cousin.