A boy and his dog, as one may say.
All spoilers are unmarked!- Any interaction between Luigi and Polterpup, ever. That big ghostly dog-grin would melt anyone's heart, and it's wonderful to see the two become best friends after all the bad blood between them in Dark Moon.
- Doubly so after you remember that back in Evershade Valley, basically all he wanted (for who knows how long) was a playmate. And now... treats, bellyrubs, all the games in the world and a master to fall asleep next to (and another to steal cake from) – unlife is turning out well for Polterpup!
- Whenever the dog saves Luigi from danger, he doesn't miss an opportunity to at the very least pat the little guy on the head.
- Polterpup actually teaches you how to use the new Poltergust G-00 all by himself, offering himself - a ghost - as a training dummy! And all without saying a word (except for the "You got that?" woof at the end). Good doggy!
- The journey to the hotel alone does an excellent job at establishing their relations in the very first scene, given that quite a while must have passed in-universe since Dark Moon. For instance, Polterpup excitedly licking and cuddling Luigi out of nowhere for no other reason than the plumber simply existing, while receiving genuine affection from him via pets in return. It gets better from there. One can only imagine how living together must be at Luigi's house.
- Through the dog's translucent body, one can see that Luigi has to push him away gently and keep petting him just to prevent getting licked more or however Polterpup wanted to show his love, so he could finish reading. It works - until the very second Luigi puts the invitation down, after which the ghost claims his owner entirely for himself.
- When Polterkitty steals the 14th floor elevator button, Polterpup goes over to her and gets in a position like he wants to play.
- After Polterpup saves Luigi from drowning after Clem floods the Boilerworks and he's barely able to swim in the surface of the water due to the Poltergust weighing him down, Luigi gives him a big hug and calls him a good dog.Luigi: Good puppy!
- Polterpup's positively huge eyes he makes when lying on Luigi's bed, watching his master the entire time as if trying to convince him to join as soon as possible.
- Polterpup once again revives Luigi if he has a Golden Bone on him... but that's not the Heartwarming part. In the previous games, he would leave right after taking the bone. Here, he sticks around until Luigi wakes up. One animation even has him push Luigi to his feet!
- Even Mario has taken a shine to Polterpup, reacting to him eating a piece of cake out of Mario's hand with a lighthearted hands-on-hips pout that shows he's just glad everyone is able to have fun.Mario: Hey, bro! (Polterpup suddenly shows up and eats his slice of cake) Awwww... Doggy!
- It's a smaller moment, but at the beginning of the game, after Luigi rescues Professor E. Gadd, the latter suggests they simply leave the hotel. Luigi, despite definitely being scared out of his wits, doesn't even consider that option, immediately shooting down the idea by informing E. Gadd that Mario, Peach, and the Toads have been kidnapped and need to be rescued (which, in all fairness, the professor wasn't aware of). It really goes to show that no matter how cowardly Luigi can be, there's nothing more important to him than the safety of his loved ones and there's no fear he won't face for their sake.
- The fact that E. Gadd named an assistant he invented for himself after Luigi. It says a lot about how much esteem E. Gadd has in the green plumber.
- When escorting Toads back to the elevator, by pressing a button while near them, Luigi will kneel down and give the Toad a high five.
- The sheer joy Morty shows both upon getting his megaphone back and on taking his film to the editing room. Despite his eccentricities, he's truly dedicated to his craft, something that creative types who play the game will surely identify with.
- Morty, after being reunited with his beloved megaphone, notices Luigi and tosses the megaphone away when he notices Luigi's appearance, saying he sees potential in Luigi to star in his film. Luigi, who has always been in the shadow of Mario, is actually complimented by someone who views Luigi as one with potential. Just hearing that is wonderful. Then after the movie, Luigi saying "I'm a star!" is absolutely adorable. Luigi is getting some of the recognition he deserves.
- For an extra moment, Luigi is able to get 100% completion and make sure Morty is happy by leaving him to his work and coming back later once his magnum opus is finished. Morty is content to go back to his frame knowing that he's finally made his impact on the world.
- Luigi floating in the rubber ducky in basement 2. He's just so cute the whole time, floating down the water.
- Mario reuniting with Luigi, literally jumping in his arms and the bros hugging each other after he's rescued from the painting, all while Mario congratulates him. He even lets out an "Awwww!" during their hug. Apart from some fan-made SFM art, this is the first time we've seen the brothers hug in (beautifully animated) 3D (The Mario & Luigi series always had 3D movement, but it's mostly in 2D).Mario: Oh, yeah! Yeah! Way to go, Luigi!
Luigi: Mario! (Mario jumps into Luigi's arms and they give each other a big hug) Hey, bro!
Mario: Awwww!- Early in the game, they wave each other "night-night" as they go to their respective rooms.
- When Mario leads the charge into the next room after refusing to be taken to the safety of the lab, Luigi, rather than shake in fear as he has most of the game, smiles and charges right after him without hesitation. It speaks volumes to just how much more confident Luigi feels knowing that Mario has his back for the last push.
- While it might also double as a Tear Jerker, if you speak to Mario before releasing Peach, the poor man sounds absolutely desperate and is practically begging Luigi to do something about it. Not only is it so surprising seeing Mario need Luigi's help for once and showing how worried he is about Peach, but it's also just so...so great to see Mario being more emotional overall.
- When Princess Peach is released from the painting, she sweetly hugs both brothers by the shoulders. One big, weird, happy family.
- A blink-and-you'll-miss-it one, but as King Boo hangs over the gang ready to throw a portrait on top of all of them and trap them, Mario just glares back at the portrait and extends his arm in front of Peach in an attempt to protect her. While they are ultimately both sealed inside, it shows that Mario is willing to protect Peach until the bitter end.
- After King Boo is defeated and all the ghosts escape containment, they and the protagonists make peace and build a new hotel in place of the old one.
- Despite being one half of the game's villains, during the end credits, a photo reveals that Hellen Gravely's containment capsule is right next to King Boo's, and she is overjoyed, having spent the whole game fangirling over him. Despite having lost everything, including her mansion and her subjects, at least Hellen got a Happy Ending of sorts for herself, even if it's at King Boo's expense...
- Much like the ScareScraper in Dark Moon providing a "good job!" talk button, this game's version has a "thank you!" button which can be used to express gratitude to being freed from a trap or for quick help on a tricky floor or boss, raising player morale and allowing you to express appreciation for a good team of random online players you can't speak to.
