Heartwarming / 10 Days with My Devil

• Throughout Rein's route it's clear that he and Haruhito miss working with each other, and they're both looking forward to the day Haruhito gets to go back to being an angel. In the end, however, Haru chooses to take the blame for Rein's actions in saving the protagonist, arguing that as Cerby's owner it's his fault the protagonist's soul got delivered to the wrong angel. What's another 10.000 souls added to his sentence, if it means his friend gets to be with the woman he loves in the meantime?
• Similarly, in Haruhito's route, Rein repeatedly warns Haruhito about repeating the kind of mistake that got him demoted in the first place, and also approaches the protagonist to make sure she knows what her presence could cost Haruhito if her death doesn't go off as it's supposed to. Although it makes him something of an antagonist for part of the route, he's obviously acting out of concern for Haruhito and the hope that they'll be partners again soon. When Haruhito rebels and runs away with the protagonist near the end of the route, Rein pops up to help delay the other demons, ensuring that the protagonist will be saved because that's what Haruhito wants.
• In Meguru's sequel, there's a flashback to the day he and Kakeru met for the first time as children. Meguru was bullied and ostracized due to being the son of the king's former mistress, and was fully expecting the same from his older half-brother when they met. Instead, it turns out that Kakeru not only doesn't care about the circumstances of Meguru's birth, but is fully prepared to defend his little brother from anyone who would hurt him, because that's what brothers do.
• In Haruhito's sequel, Kakeru offers the now human Haru a chance to go back to being a demon, while Rein offers to convince his superiors to let Haruhito back into the angel fold. In the end, Haruhito chooses to become a demon again, and the scene where he explains his choice to Rein and the two of them decide that, even if the former never becomes an angel again, it won't change their friendship is very sweet.
  • In the same scene, Haruhito and Rein discuss how great it would be if angels and demons worked together as partners and promise each other to help create a world where angels and demons get along as well as they do. Implying that there's still a chance for them to become partners again.