"I was born in the Jungle. I have obeyed the Law of the Jungle, and there is no wolf of ours from whose paws I have not pulled a thorn. Surely they are my brothers!" (1.79)
Surely, right? Not so much. This line foreshadows the stinging betrayal Mowgli feels when he learns the wolves are not his brothers, and they kick him out the first shot they get.
The Lone Wolf must have sprung and missed his hold, for Mowgli heard the snap of his teeth and then a yelp as the sambhur knocked him over with his forefoot. (1.100)
The wolves don't just betray Mowgli, they betray their own leader by humiliating Akela with this Sambhur, all to convince everyone else he is unfit to lead.
"I promise that when I am a man among men I will not betray ye to men as ye have betrayed me." (1.134)
Mowgli takes the moral high ground, deciding not to betray the wolves even though, as a man, it would be very easy to do so.
"Have a care, Manling, that I do not mistake thee for a monkey some twilight when I have newly changed my coat." (3.137)
Kaa, being a snake, has no problem betraying the trust of Bagheera and Baloo by eating the child they asked him to save, but Mowgli bargains his way out of it.
"I will always remember that I have been cast out of the Pack." (5.21)
This is Mowgli nicely telling the wolves, "I wouldn't pee on you if you were on fire." He'll never forget the way they turned against him.
"Sorcerer! Wolf's brat! Jungle-demon! Go away! Get hence quickly, or the priest will turn thee into a wolf again. Shoot, Buldeo, shoot!" (5.89)
Poor Mowgli—even the humans turn against him, too. Unlike the wolves, who just kick him out, the humans try to kill him, though.
"Again? Last time it was because I was a man. This time it is because I am a wolf." (5.95)
Mowgli seems exasperated here. He doesn't know where he'll ever fit in, because both sides of his life, man and wolf, have betrayed him.
"Ye fought for freedom, and it is yours. Eat it, O Wolves." (5.111)
Bagheera reminds the wolves that once they betray their brothers and their leader, they don't deserve either. They're on their own.
The holluschickie and Sea Catch, his father, and all the other seals, laughed at him when he told them what he had discovered. (7.90)
Kotick spends years of his life searching for a safe beach, and when he finds one, all the other animals laugh at him. If they did that to us, we'd probably leave them to become coats, but Kotick handles the humiliating betrayal with honor.
Kala Nag saw [Little Toomai], caught him in his trunk, and handed him up to Big Toomai, who slapped him then and there, and put him back on the post. (11.14)
Big Toomai is not happy that Little Toomai is doing a good job. This sounds counter-intuitive, but father has asked son to not be good at his job so that he doesn't get taken away by Petersen Sahib. Little Toomai betrays his father by being resourceful.