The resolution of each Character Arc in the final area, if you've watched the corresponding memories. They come with perks, too:
Hiante and Snowe talk about Hiante's former life. Hiante has basically come to terms with it, and says that he's glad to know that he was someone and not just a pile of bones that Edgar threw together for a quick bodyguard. He theorizes that his wife and daughter were smart enough that they probably were able to tell that things were going south and left the island, and he expresses gratitude for being given a second chance by being able to raise Astra.
Relenia reunites with her daughter. If you try to talk to either of them, Snowe refuses to, noting that they're catching up and he should probably leave them be. And Anastasia's reaction when Relenia, after a lot of dithering, finally approaches:
Anastasia: What took you so long?
Snowe and Richard talk, Richard apologizes for all the mistakes he's made in the past but Snowe says he doesn't blame him for any of it, and then Richard, who has been a Parental Substitute for Snowe for years, more or less officially adopts him right there.
Astra expresses thanks over being able to leave the tower after all, and when she learns of Snowe's nightmares, sends him to see Erio. When Erio and Snowe complete the Nightmare dungeon, Dream Astra gives them a very powerful spell to give to the real Astra.
Astra's memory, where it's revealed that Erio and Hiante risked their lives just to make Astra happy — and indeed, Erio was punished severely for teleporting Astra to the flower grove. The picture even shows Erio smiling, which never happens anywhere else in the game!
The short story "Stars in the Distance" is adorable. For one thing it goes into Astra's memory in more detail. When Hiante and Erio tell Astra they have connected their thoughts so that they can continue taking her to the flower grove without Lina or Edgar finding out, Astra immediately hugs both of them. The whole short story actually mainly concerns itself with Erio and Hiante going well out of their way just to keep Astra smiling. And the way it ends is adorable too.
In the Sepulcher, after Astra, Hiante, and Relenia are freed from prison, they run into Numismatist. She notices that Snowe's missing and immediately expresses concern, saying that she hopes they find him. It's too soon for him to be a ghost, she thinks. And when you walk there after getting Snowe back, she says she's always happy to see him. It's notable because the first time they ever spoke she out and out told him she didn't like him.
In "A Demon", Astra is incredibly sweet and friendly to Erio the first time she meets him, which he probably needed after he'd just had a very, very bad day.
In "A Spell of Fire & a Scarecrow", Xiri first helps Snowe build his snowman, and later Richard helps Snowe put the finishing touches on it. When Richard comments on the height of the snowman, Snowe tells Richard that "Snowman can't be short! They have to guard the castle!"
The demon Erio has Snowe and Relenia help him call upon to save them when the Sepulcher falls to pieces around them is actually his older sister. He wasn't sure it would work and worried that this demon was angry at him for wandering off and not coming home for ten years, but it turns out that whether or not she's angry at him, she still is more than willing to save the lives of him and his friends. It becomes heartwrenching in the bad ending sequel, where it's learned that all Soria really wanted was for her brother to come home.
Hiante standing up against the Original King in the flashback turned out to have inspired others to do the same. It didn't change the outcome in any way, but it's still quite touching.