Ferris: Fool. If you died... you know I'd be lonely.
Ryner defending Ferris from Tiir and the God's Eyes bearers, telling them just how much she's stood by him and presenting her as living proof that not all humans are as bad as they think they are. Even Tiir admits that if there's one human he could believe in, it would be her.
The end of the anime, with Ryner vowing to to never give upon Sion and that he'll catch up with him and repay him for saving him from himself.
Ryner coming to save Toale, despite the fact that even calling them friends would be somewhat of a stretch, seeing as how they only met once. Considering how cornered and stressed out Toale was, it's understandably one of the better pieces of news that he's heard in a while, in spite of his initial suspicion.
On that note, Toale dropping honorifics once to show that he fully trusts Ryner also counts.
The short story Dear My Sister, showing just how utterly grateful Fiole is to Sion. He names Sion as one of the people he'd protect with his life alongside Eslina and as his new reason to live, also throwing in an Ironic Echo as he cites that he's truly glad to have been born in this world and country in spite of his cruel death.
Tiir finally choosing to believe in Ryner's judgment and agreeing to have faith in Ryner's friends. Ryner returns the favour when Tiir points out how the other God's Eyes bearers won't trust humans so easily by claiming Tiir to be the true king of Cursed Eye bearers, and that if Tiir chooses to have faith in humans, everyone else will follow.
While his development is then undone in the next volume, it repairs itself with another moment as Ryner again asks Tiir to become his ally, even throwing in an Ironic Echo as he holds his hand out and uses the same lines Sion used on him—to join him and become his ally, as he'll change the world into one they want to see.
Arua's father telling Arua to keep on living. Perhaps a minor one, but considering the amount of prejudice that Cursed Eye bearers go through, even a simple act of kindness is significant. Similarly, the fact that Kuu never wavers in her support of Arua in contrast to one of Ryner's first friends, who turned her back on him even after what she went through.
Upon being given the chance to break free from Milk's brainwashing, Luke purposely chooses not to, despite the fact that he supposedly lacks emotions, meaning that he should be incapable of acting irrationally here. However, he'd rather keep on feeling this way towards Milk, even if it's a lie, proving that he does have feelings in spite of what Lieral says about him.
The Taboo Breaker Pursuit Squadron as a whole, considering how close they are with one another and their declaration that they're a family. Their efforts to give Milk the life she never had are also rather sweet.
While Lucile generally indulges in twisted and psychopathic behaviour, he has a few genuinely sweet moments with Ferris.
He offhandedly invites Sion over for breakfast, in turn making Ferris happy. On top of that, just seeing Ferris and Iris enjoying themselves is enough to reinforce his belief that essentially sacrificing his humanity was worth it, as long as they're happy.
Him saving her and Iris from Froaude, reassuring Ferris that he'll protect them.
In a reverse moment, Ferris initiates it by telling Lucile after his attack on Ene that she does care about him and wants to help him. Considering how tense their relationship has been, it's a reminder that no matter how far Lucile falls, Ferris does still love him as her brother.
A small moment where Lucile and Sion show that, in spite of not quite getting along, they do have a connection of sorts—after Lucile fails to protect Sion from the Goddess Milk, he apologizes for his failure. Sion tells him not to worry about it, as Lucile always puts up with his weakness, and that they have to be there for each other.
The full story of the Mad Hero aka Asruld and the Lonesome Demon aka Ryner Eris Reed. At the very end of things, Asruld tells Ryner that he's glad he's there with him, or else he might've gone insane otherwise. Considering that all Asruld cared about before was destroying everything, it's a notable moment for him.
The fireworks scene in the anime—with Claugh and Noa holding hands, the Taboo Breaker Pursuit Squadron holding their belated birthday party for Milk, and everyone just looking so happy and at peace for once. There's also a brief Tear Jerker moment where they show Fiole's grave.
The flashback of when Riphal, Lize, and Lir were teenagers, joking around while making their plans. Considering some of their actions in the present, it's a reminder that all of them—even Lir—are still human at heart and just how close-knit the people of Gastark are, after what their country went through.
Ferris and Ryner's letter to Sion asking to meet up and form an alliance. Even aside from Ryner talking about how he wants to change the world together with Sion, the sheer normalcy of their messages, after all they've been through including being estranged/enemies for the past months, makes the entire thing rather sweet.
After Tiir's fight with Lieral, with Tiir later trying to convince Ryner to come with them and even Ferris thinking there's merit in that, Ryner chooses not to, stating that his place is right here—where his friends are.
Lucile and Ferris finally reconciling after years of tension. The entire thing goes between incredibly sweet and adorable, with it ending with Ferris crying into Lucile's chest out of happiness.