Most interactions between any dragon and their captain/companions, which is usually of absolute, mutual devotion and love. Just imagine a huge, intimidating dragon cuddling up to their favorite person in the world. Aww!
The Temeraire series gets one early, near the beginning of His Majesty's Dragon, and as the series progresses and you see the depth of their friendship it only becomes more poignant. During a discussion of how dragons like hoarding and how Laurence is not particularly wealthy, Temeraire says, offhand, how he would rather have Laurence than any heap of gold.
He said it quite normally, not in the least as though he meant to deliver a compliment, and immediately went back to looking at clouds; Laurence was left gazing after him in a sensation of mingled amazement and extraordinary pleasure. He could scarcely imagine a similar feeling; the only parallel he could conceive from his old life would be if the Reliant had spoken to say she liked to have him for her captain: both praise and affection, from the highest source imaginable, and it filled him with fresh determination to prove worth of the encomium.
This troper never fails to cry at the ending of His Majesty's Dragon's first part. Essentially, the aviators tried to separate Laurence and Temeraire, but Temeraire wasn't having any. Being a dragon, he pitches one hell of an impressive hissy fit, bringing Laurence running back. Then...
"If you would like to have your ship back," Temeraire said, "I will let someone else ride me. Not him, because he says things that are not true; but I will not make you stay." Laurence stood motionless for a moment, his hands still on Temeraire's head, with the dragon's warm breath curling around him. "No, my dear," he said at last, softly, knowing it was only the truth. "I would rather have you than any ship in the Navy."
There's also the bit at the end of His Majesty's Dragon, when Laurence and Temeraire go to what they think will be their deaths, for duty and to try and save their friends. Of course, then Temeraire gets his Crowning Moment Of Awesome and all bets are off...
It's a rather small gesture, but one of this troper's favourite bits is when Laurence presents Temeraire with his chain and seeing how happy Temeraire is when he gets it. And when Laurence goes back to find Temeraire after he rejects Lieutenant Dayes, Laurence finds Temeraire dejectedly curled on the floor stroking his chain...
Temeraire again, with a bittersweet moment coming after the tragedy of Levitas' death. Lenton is concerned that Rankin will almost immediately harness another dragon, a soon-to-hatch Winchester in Chatham. Laurence recommends Hollin for the position instead:
Lenton, about Hollin: "Not a gentleman, I suppose?" Laurence: "No, sir, unless by gentleman you mean a man of honour rather than breeding."
Laurence and Temeraire's reunion in Victory of Eagles.
Temeraire bent down his head and peered at Laurence very closely, and put out his tongue experimentally to sniff at him, and then at last he cautiously, so cautiously, put out his forehand to curl about Laurence and lift him up, and oh, he was quite solid: he was there, and he was not dead at all, and Temeraire gave a low joyful cry and curled around him tightly and said, "Oh Laurence; I shall never let anyone take you from me again."
In Tongues of Serpents, when the little egg hatches, he is unfortunately disfigured, weak, and cannot fly.Rankin wants to kill him, but first Laurence steps in to provide for the hatchling, despite the wedge it would create between himself and Temeraire. But then,
He turned, and stopped: the hatchling was feasting...[on] kangaroo, with a loop of belt around its neck for token harness, and Demane looked up and said, "I am naming him Kulingile. It means 'all is well.'"
Demane and Emily's entire relationship. Considering the time period, this is absolutely unheard of, and the fact that the feelings are mutual between them just makes it sweeter.
Two thirds of the way through Blood of Tyrants, after Temeraire has inadvertently revealed to the amnesiac Laurence his treachery against Britain in Empire of Ivory. Laurence gets a Heroic BSOD, but soon gets over it, and goes to find Temeraire, who has since begun considering the negative impact he's had on the lives of those around him. When they next meet, Temeraire tries to apologise to Laurence for his role in his treachery and the loss of his fortune, but Laurence reassures him that he doesn't care. Temeraire finally offers to let Laurence leave him, feeling he'd be happier if he'd never harnessed him, but Laurence denies this; stating he wouldn't change anything that's happened to him, even if he could.
In fact, his enlightened sense of his role in life (obtained as a result of his amnesia) is one big CMOH as, at the close of part 2 Laurence admits to himself that he's glad for the way he has changed in the last 8 years, treason included, when he says goodbye to Granby and Little, with the latter very unsure of Laurence's stance on their relationship now that his memory has returned. While the Laurence of 8 years ago would have reported cases of fraternization like theirs despite the hell it would unleash for the individuals involved, the Laurence he is now would gladly overlook the rules. He then wishes them all the luck as he says goodbye.