One of the bonus strips shows Adrien looking sparkly-eyed and excited to be a superhero, unaware that he'll soon be saddled with an Alpha Bitch partner who takes all the credit for his victories. After only a couple of chapters, he's been left burnt out dealing with the mess on his own.
Sabrina has Dull Eyes of Unhappiness throughout "Darkblade," showing she still isn't over how her father was fired because of her "best friend." She then cries tears of guilt when Sabine tries to cheer her up with a free bag of cookies while Sabrina's trying to sneak into the woman's daughter's room for blackmail material.
Lila gets utterly humiliated and thrown into a fountain in the middle of winter by a vengeful Scarlet Lady in front of not only Adrien, but also her other classmates. To add insult to injury, she also catches a cold.
Adrien barely even reacts to the high likelihood that his own father is Hawkmoth. It really shows how jaded he's become if a major revelation like this hardly even phases him.
During "Evillustrator," Chat Noir, after having to save Marinette and himself following a claustrophobic breakdown, hugs her and practically begs her to not participate in anymore akuma fights out of fear for her safety. Marinette is so stunned by Chat's Moment of Weakness, she can't help but agree to try.
When Marigold goes for the traditional Fist Bump from canon, Chat... doesn't reciprocate his new ally's gesture. He professionally thanks her for the help and then leaves, leaving Marigold shocked and saddened. While it's expected of Chat to be wary of new help given his bad experiences with Scarlet Lady and Volpina, it still hurts considering it's Marinette under the mask.
A downplayed and possibly unintentional example on the header picture for "Riposte." Kagami is crouching and holding her hand out with a sad expression on her face. It makes you want to give the poor girl a hug.
At the end of "Intermission," Marigold and Chat Noir reflect upon how Tikki, much like Nooroo, is stuck working with somebody who likely sees her as nothing more as a means to their own selfish ends. Chat Noir notes that Plagg has suggested Tikki will prioritize Nooroo's safety over her own, and all Marigold can do is note how unfair it all seems.
On the other hand, to wield her true Miraculous, Marinette might have to give up Pollen despite the genuine friendship they've formed, with the Kwami not having been this well cared-for in years.
After Marinette recovers her and brings her to Master Fu to be healed, Tikki gets to share a hug with the person she knows is her true bearer, but due to the rules, she is not allowed to tell Marinette that. Needless to say, Tikki ends up crying a little.
The events of "Despair Bear" have damaged, if not outright shattered, Scarlet Lady's (undeserved) image as a beloved superhero. Good news for the heroes who need her reputation smashed before they can get the Ladybug Miraculous away from her. Bad news for all the people who have had their misguided view of their superhero ruined, especially Alya, her biggest supporter, who can't even respond when Marinette tries to ask her something and has to take time to process what she's seen.
Kagami's mother reveals in "Ikari Gozen" that all her friends abandoned her after she became blind—that's why she doesn't want Kagami to have friends.
The Reveal that the reason Anarka and Jagged Stone broke up was because Bob Roth faked a pair of Dear John Lettersafter Anarka told Bob that she was pregnant. While the couple's reactions to this is Played for Laughs, it's sad to learn that Anarka and Jagged lost a good relationship and that Luka and Juleka grew up without a father all because of one man's greed. Even after the two reconcile, Jagged openly admits that there's practically no chance things can go back to the way they were before.
Marigold's despair at getting everyone caught in "Robostus," saying she's sorry when she's about to lose her Miraculous.
While it was kind of her fault, it's a little hard to watch Nadja break down in tears after the disastrous interview in "Prime Queen," especially since the producers were the ones who pushed her into being invasive with the questions. Meanwhile, Marigold looks heartbroken because she had kissed Chat Noir, and not only does she not remember it, but Chat Noir states it meant nothing because he only did it because of the akuma. Chat Noir realizes a bit too late that he hurt his partner with that statement. It gets even worse when Marigold admits her true feelings on live TV when Nadja turns into Prime Queen, and when Chat initially thinks she's lying, she says:
Marigold: Superheroes don't lie, Chaton. Chat Noir:[blushes in embarrassment]
It gets worse when Bustier gets akumatized and targets Marinette because she couldn't handle her student calling her out on being an ineffective authority figure, driving home how the teacher responds to bullying by Blaming the Victim.
Ivan: If you mess up a little, she sends you to the principal. But I knew I'd look like the bad guy if I said anything negative about the "nice" teacher.
It's really sad and bittersweet to see the kids complain about Bustier's methods when the episode started with them all bringing her birthday presents.
After Alya falls to one of Zombizou's zombies and Nino stays behind with her, Marinette breaks down crying, wondering why her friends didn't try to protect themselves and chose instead to sacrifice themselves to protect her, which becomes worse when Chat Noir (who had just declared his intention to keep her safe) gets infected while trying to protect her from Scarlet Lady.
After defeating Zombizou, Marigold falls on to Chat's chest, crying after the whole distressing experience.
The ending of "Gorizilla" highlights the emotional distance between Gabriel and his son, with Adrien flat out telling his father that he's never given Adrien a reason to trust him.
The various nightmares shown in "Sandboy" tend to be this:
Marigold's nightmare is becoming powerless—a clear sign of how much the events from "Zombizou" (in which all of her friends slowly got infected by the akuma while she was unable to transform) are still weighing on her mind.
Meanwhile, Chat Noir's fear is Marinette being akumatized. Not only that, but it's implied it happened because he wasn't there to prevent it.
The end of "Reverser" reveals Pollen already knows that Tikki was meant to be with Marinette instead of her... so if things go back to how they were meant to be (which seems very likely at this point), Pollen will probably have to say goodbye to the Queen she loves so much. Pollen has already quietly and sadly accepted this, but she can't even tell her beloved Queen about it.
"Party Crasher" makes Wayhem's akumatization much more sympathetic; when he's drawn to the manor by all the ruckus, he thinks Adrien lied to him when he claimed that he'd be busy earlier, as well as when he said that he wanted to introduce Wayhem to all of his friends. Naturally, Hawkmoth takes advantage of this in a bid to restore power to his lair. The situation also doesn't get resolved on-panel, as Wayhem disappears after being dealt with. Meaning that as far as the audience knows, he never learns it was all a misunderstanding.
In the bonus image for when Clara is akumatized, two people are shown being frozen, devastating their (girl)friends:
Kagami is shown telling Aurore to run just before being frozen while Mireille tries to pull her friend away from danger.
Juleka clearly attempted to protect Rose, as she's become a statue as well while poised as a Human Shield. But Rose still got hit, and she's clearly crying for her girlfriend as she begins to sing "I Love Unicorns" in an attempt to avoid sharing the same fate.
At the beginning of "Queen Wasp", Gabriel makes the uncharacteristic step of hugging Adrien in public while crying, which Adrien thinks is because his father was afraid of losing him to Style Queen... when the actual reason Gabriel's crying is because he's frustrated Style Queen failed. If the previous episodes weren't enough to prove that Gabriel is a horrible person, this is proof enough.
Downplayed. Although Marinette has finally received the Ladybug Miraculous and even gets to keep Pollen as well, she can never be Marigold again, marking the End of an Era.
In "Catalyst", Nathalie creates an illusion of an akumaized Chat Blanc vaporizing Marigold with cataclysm, which quickly drives the watching people into despair and panic.
The two that really drive it home are Alix's and Kim's.
Kim calls Ondine, who is seen crying as she informs him that there are a lot of Akumas around and Kagami already turned. The last thing Kim hears is Ondine screaming at an Akuma to stay away, which causes Kim to become Akumatized as well.
After Koki Marina gets hit trying to protect Fox Trot from Dark Cupid's arrows without using her shield, the other heroes try to prevent any of the red swarm from reaching and akumatizing her. When they fail, Fox Trot promptly stops resisting, overcome with grief at his failure to protect his girlfriend.
Vesperia gets ambushed by Despair Bear and is the next to fall, complete with a close-up shot of the Comb in her hair as she falls under Scarlet Moth's control. This doesn't seem likely to do much for her self-esteem issues...
Timebreaker is among the akumas held back by the civilian blockade; Sabrina and Lila manage to take her down, binding her hands behind her back before embracing her and tearfully apologizing for not realizing how upset and scared she was sooner:
Sabrina and Lila:We're so sorry, Alix! Timebreaker: ?! Lila: You've always been so cool, we didn't think you'd need our support. Even though you've always supported us! Sabrina: You're our best friend, Alix! You saved us! So we want to save you! You don't have to be scared with us!
Ondine's reunion with Dark Cupid after being purified. The moment he sees her, he immediately stops fighting, tears filling his eyes as he apologizes for not being able to protect her.
Dark Cupid: Ondine... you're okay...! Ondine: Yes! I'm sorry Kim, I scared you so, so bad— Dark Cupid:NO! I WASN'T THERE FOR YOU! I COULDN'T PROTECT YOU! I'M SO SORRY! Ondine: It's okay now, right? You did nothing wrong. So, can you go back to being my boyfriend, please? Kim:(reverting back to normal as they embrace) Yeah... I don't want to help Hawkmoth anymore.
Sentiwasp's death. Once Ladybug gets her hands on the bracelet that serves as her amok, Blue Blood casually dismisses her with a snap of her fingers. There's no hesitation, no remorse; so far as she's concerned, her counterpart is nothing more than a tool that's no longer useful.
Once Gabriel is unmasked, Nooroo timidly murmurs "Master..." Not only does he look sincerely saddened, expressing some sympathy for the man who's been abusing him and his powers, it stings seeing him continuing to address Gabriel in such a fashion.
Later, he hides behind Ladybug's arm while she's ripping Gabriel a new one, visibly trembling.
In a weirdly satisfying moment, Chat Noir has no reaction to learning his father is Hawkmoth. While he may just be bottling them up to keep anyone else from discovering who he is, the complete and utter lack of anything implies that Adrien no longer even cares for Gabriel after everything he's done.
He's shown with Hidden Eyes as Ladybug calls Gabriel out on how he'd left his son to mourn his mother's apparent death alone, without sparing a single thought to supporting him in his time of need. Beside him, Fox Trot is trembling with rage; as laidback as Nino generally is, Gabriel hits every one of his Berserk Buttons.
As they return their Miraculouses, Alya and Nino wonder how well Adrien is going to handle the news that his father was the very same supervillain they've just defeated. Chat Noir attempts to reassure them that Adrien will surely focus on the positive aspects, and is clearly stunned when his friends angrily defend his right to be upset or even grieve over losing his dad. It's a stark reminder of how much Adrien is accustomed to swallowing down his feelings and acting like a Stepford Smiler; even after all the time he's spent with Nino, Alya and the others, he's not used to anyone saying he's allowed to express himself in ways that don't pander perfectly to the camera.
When Fu expresses his apologies for who Hawkmoth turned out to be, Adrien tries to claim he's okay, but then Marinette comes and tells him not to say that unless he means it. Adrien can barely hold it for a few seconds before he finally breaks down crying, holding onto Marinette as she, Fu, and the Kwamis hug him.
Right after Marinette summons up her courage and shares a Big Damn Kiss with Adrien, he gets a call from Nathalie that brings up the otherElephant in the Living Room: just where is he going to stay now that his father's been unmasked as a magical terrorist? When he brings up the possibility that he'll have to move to London and stay with his Aunt Amelie, Marinette and the others start frantically offering to let him stay with them, bringing Adrien to tears at how many of them are desperate to help him stay in Paris despite everything.
The moment Adrien is not nearby to listen, Emilie demonstrates that she's as much of a Control Freak as her husband, only she hides it beneath a "loving" mother faƧade playing Good Cop to Gabriel's Bad Cop. And, given Nathalie's reaction to this, it appears that she doesn't even care. While Word of God is that Adrien's Character Development has allowed him to wise up to Emilie's methods, and that without Gabriel she's just annoying, it's just another demonstration of how badly his pre-series life must have been - and that he cannot count on the adults in his life to actually provide the emotional support he needs.