Heartwarming / Pokémon Reborn

• Serra and Radomus both adopting Luna and raising her as they would if she was their own daughter. Heartwarming by itself, but Luna was never adopted normally; she randomly appeared on both Radomus's and Serra’s doorsteps one day, out of the blue, and in Radomus's case, she turned out to be related to El, who is an old rival of his and may have brought up memories of losing Noel and Anna. Neither let it stop them from caring for her.
• Though YMMV on it, your first encounter with Saphira is this. The first time you meet her, she’s in front of the Orphanage muttering about how she’ll get revenge. Alarming? Not so much, when you learn her little sister Laura was turning 18 and leaving that day, as well as how Dr. Connal acts towards his charges…
• Anna comforting Laura when she begins to cry after explaining how her mother and father died.
  "Tears are people’s way of getting the sadness out of their bodies. Just because you’re an adult doesn’t mean you can’t cry."
• Shelly going with you up to Ametrine to try to find Heather. A true indicator of how much she cares for her friend.
• On Mt. Ametrine, Cal reassuring Shelly that he isn’t going to hurt her any more, and that he’s trying to put the past behind him.
• Heather is locked up in a mountaintop shed, quietly criticizing herself for driving everyone away, admitting that it was her fault. Then, you and Shelly show up and break her out.
  Heather: Thanks for coming for me.
  Shelly hugs Heather.
  Shelly: Of course! That’s what friends do, right?
  Heather: Yeah. <looks away> I was never much of a friend though.
  Shelly: You were to me. You were all I had.
  Heather: Shelly, I’m sorry –
  Shelly: It’s okay! Don’t worry. Someone just told me, everyone makes mistakes. Nothing can change the past, but we can always fix the future. So, I forgive you. I’d forgive him too.
  Heather: Right… thanks.
• Shelly nicknaming her entire team after her friends and her brother by the time you reach Mt. Ametrine. When we first met her, her only friend was Heather. Now, she has a lot more. By the time of the Glass Workshop gauntlet, she has named one of her Pokémon, her Leavanny, after the player character, too! That same Leavanny is in her Championship team years later, during the alternate timeline of the Celebi quest, in which the player and Elias vanished without a trace. She never forgot her friend.
• The rebuilding (Rebirth?) of Reborn City. It may have taken 15 episodes, it may have taken a huge amount of effort from almost everyone, you included, but it’s beautiful to see what all that work brought out from the former Wretched Hive. There are still complaints, and flaws, people who need help or who don’t want to help the rebuilding, and the process is ongoing… but overall, considering the city was a complete Crapsack World before, it changing to become A World Half Full is amazing. A reminder that, for all the horrible things people like Team Meteor can do… it’s also possible to do things like this.
• Serra establishing herself as a Mama Bear for her son Bennett, no matter how different the two are.
  Gardevoir: That’s right, you gave up your career for your son before. Do you regret doing that?
  Serra: It’s hard to say. I think the best way to put it is that, although I do feel remorse for what I’ve lost, I wouldn’t change my decision even if I could. There are more important things than passions and careers.
  Gardevoir: You mean your son, of course. How touching! But, tell me, how do you respond to the recent developments wherein he’s fallen in with the terrorist organization Team Meteor?
  Serra: I’m sorry. He’s what?
  Gardevoir: In his recent exploits, it seems likely he’s been working under and assisting Team Meteor in destroying the region!
  Serra: He’s — …Gardevoir, take me to Bennett.
  Gardevoir: Ah, in time, but let’s finish the interview first?
  Serra: Gardevoir. Take me to Bennett.
  Gardevoir: …Yes, missus.
• Radomus, Serra, Luna, and Gardevoir all meeting up for the first time at the Glass Workshop before they enter. Even if it's the first time they've all been in the same place at one time, and despite Serra's lack of faith that anything will come of it, it's very sweet to watch the four interact.
• Initially things are looking bleak for Radomus and Serra in the Glass Workshop, who just saw you defeat both them and Luna, and then watched Gardevoir unleash a black hole in order to destroy the PULSE Hypno, seemingly killing herself in the process along with you, Cain, and Luna. Then, Shade appears out of nowhere with you in tow, and things start looking up.
  • Cain, Gardevoir, and Luna are all alive inside of the void, and Luna herself helped you escape, which was likely a relief to both Radomus and Serra, her adoptive parents.
  • Anna and Noel show up, and as it turns out, Radomus is their father!
  • Lumi and Eve reappear after their Uncertain Doom after the PULSE Magnezone's destruction, turn out to have been Good All Along, and start helping you fight Team Meteor.
• Fern and Florinia, after your Umbral battle with the former, finally agree to start working through their issues. And Fern finally admits to his failings, and tells Florinia that, well - he's happy Florinia's hurt, because it means she does still care deep down for him. And he wants to do better. Florinia's response?
  Florinia: ...T-too much to process.
  Fern: Take your time. I'm here for it.
  Florinia: Confused. Sad. Relieved. Angry. Happy. Scared.
  Fern: ...Yeah, me too. All of that. Maybe for now, that's okay?
• In the post-postgame "Another Time" segment, among the people you can talk to are the Agate Circus Trio, whose relationship seems to be on the verge of marriage... Judging by the wedding dress that Terra has been wearing for a month straight. Also, the fact that both Samson and Terra have reached out (to Noel and Serra, respectively) to try to commission elaborate engagement rings.
  Samson: Terra's a handful. And between you and me, so is Ciel. But... life is pretty good. They bring out the best in each other. And I hope they bring out the best in me, too.
• Just the fact that after everything that's happened and everything you've been through, you can give nearly everyone a happy ending.