- Many of the boy's interactions with Trico. For one thing, if you press the use button while standing next to him, the boy starts petting Trico affectionately while Trico nuzzles up to him in a way that's absolutely adorable. This is also necessary, as whenever Trico defends the boy, he becomes riled up and you can't progress until you calm him back down, which is also heartwarming.
- If it wasn't adorable enough, sometimes when Trico nuzzles the boy, the boy giggles and says his name affectionately.
- Have the boy look at Trico after he shakes his armor off at the very beginning, and the boy will cheerfully say, "So that's what you look like. Nice to meet you, Trico." which might be followed by Trico nuzzling him for the first time.
- If you climb up on Trico and pet his neck or the top of his head long enough, he'll lay down and fall asleep.
- The narration itself in general. The boy, as an adult, fondly talks about how he and Trico formed a bond and a mutual understanding that helped them in their journey. It shows that despite the years following their separation, he still hasn't forgotten about Trico. The ending also implies they will be reunited.
- The narration also reveals some little details. The part where Trico jumped and climbed without any orders after you did? Trico grew accustomed to the boy to the point of starting to mimic his movements.
- After Trico and the Boy's second encounter with an antenna chamber, Trico assumes the Boy is dead, but gently nudges and moves him around before placing him in a puddle of water, attempting to wake him. Trico quite literally jumps for joy when the Boy does wake up.
- The third time you enter the antenna room, Trico refuses to let it control him again, resisting it until the boy uses the shield to destroy the device. Stand in front of Trico afterwards, and he will bend down to nuzzle the boy, thrilled that he's okay.
- In a mix of this and Awesome: throughout the game, the boy occasionally has to get rid of some eye-glass things that Trico is afraid of. At one point, the evil robot soldiers outnumber the boy and takes him away while others are holding the glass eyes to prevent Trico from helping him. The bond between the boy and Trico has grown so strong at this point, however, that Trico manages to ignore his fear and leaps in to attack, freeing the boy.
- The moment after you defeat the Master of the Valley, and the other Tricos snap out of it. Rather than tend to its wounds, your Trico checks to see if the Boy is alright.
- After the long Solo Sequence, when you're reunited with Trico in the other Trico's nest. You're trapped in a cage, but Trico is so happy to see you that he tries to nuzzle you through the bars anyway. It then becomes funny when Trico realizes the cage you're in rolls and he bats you around a bit—gently, of course, but still like a giant cat with a ball of tin foil.
- After the companions' third encounter with the dark Trico, your Trico is left a beaten, exhausted mess on the ground, and you spend some time giving Trico barrels while he's so weak he can only grab them while the boy holds them to his mouth. Petting Trico results in the boy saying his name in a sad, worried tone, and Trico will stir and whimper in response to his touch. After having fed Trico enough barrels, the scene pans away to reveal Trico and the boy proceeding to fall asleep next to each other the entire night, the boy curled up by Trico's tummy.
- The epilogue. Several decades later, the boy, now an aged man, rediscovers the magic shield after a group of village children find it buried into the ground. Wielding it again for the first time since his adventure as a child, he points the mirror skyward as the camera travels all the way back to the Nest, into the dark chamber from the start of the game. Suddenly, Trico's familiar glowing eyes emerge from the darkness, accompanied by a second pair of eyes. Not only does this imply that Trico is alive and well, it appears that it now has a child of its own.
- If you press the circle button when the camera pans into the cave, Trico's horns will light up as well. It's as if he's directly responding to the player, telling you, "I hear you". [Tender Tears]
- The mere scope of what makes it cinematic and beautiful: the fact that the entire sequence tracks from his village all the way to Trico's cave is a testament that no matter how many years, no matter how far apart they've been, sometimes friendship can span years and distance.
- The mere fact that the game finally released was heartwarming enough for many of the people who followed it for years. Many saw it as a bright spot in the otherwise disappointing year of 2016.
Heartwarming / The Last Guardian