In all honesty, you likely wouldn't consider biting somebody to be very polite. There are much better ways in showing somebody how much you like them. Yet there are some characters that consider biting somebody as a way of showing their love.
They don't mean any harm. They just really like the person they are biting. This love isn't because they think they taste good either. They just really like the person they are biting and are looking at the bite as being friendly.
Very much Truth in Television with the existence of hickies, and there are plenty of animals who will bite to show that they love you. Fair warning though: Some animals don't know how to bite softly. It's also known as the condition Odaxelagnia in Real Life.
- Justified in Horimiya. Hori bites Miyamura on the back of the neck during Their First Time, partially out of affection and partially to encourage him to grow his hair back out (since it'd be the only way for him to cover the mark).
- The bunny-girl Carrot from One Piece is an energetic Genki Girl who greets people with abandon, and almost always with a bite. Though mildly painful, the bites are never deep or injurous, and never draw blood or leave a scar. Unless someone takes her carrots; then she'll bite that fool's head clean off.
- Pokémon: James' Carnivine, following the trend set by his previous Grass-type Pokemon, would hurt him to show its affection. In this case, it would always bite down... on his head.
- In Zombie Land Saga, Tae is the only zombie who hasn't regained her human consciousness and will often bite things or people (harmlessly) just because. One of the last scenes in the first season has her happily chewing on Sakura's head while the latter is talking.
- Books of the Raksura: The titular species of slightly draconic Humanshifters give each other gentle bites as their version of kissing.
- Harry Potter: Harry's faithful pet owl Hedwig shows affection for her master by gently nipping his hand or ear. When Harry is rude to her, the nips are a lot less gentle.
- In E. T. A. Hoffmann's Master Flea, the titular character offers to bite Peregrinus in the finger as a sign of friendship, since obviously they cannot shake hands.
- The Parasol Protectorate: One of the early hints Alexia Tarabotti gets as to Lord Maccon's feelings for her is when he ends up giving her some love bites in an empty street in the middle of the night. She decides to pay him back later.
- A Series of Unfortunate Events: Sunny Baudelaire is notable for biting anything she gets her hands on, and people are no different. How she bites them is how she shows her feelings. If she bites hard, she hates them. If she bites soft, she likes them.
- Xandri Corelel's parrot Cake occasionally nips her. She has to blow on him whenever he does it so he doesn't develop a habit.
- Doctor Who: In "The Doctor's Wife", the TARDIS's soul is forcibly ripped out and placed in a human body. When the TARDIS next bumps into the Doctor, she kisses him and then gets the idea to bite him, gleefully declaring "It's like kissing, only there's a winner!"
- The Punisher (2017): In "One Bad Day", during Billy and Dumont's intimate scene, she is nibbling on his shoulder.
- Star Trek: The Next Generation establishes that this is a common element of Klingon foreplay. In general, Klingon romances are somewhat violent compared to those of humans.
- The Wild Thornberrys has an episode in which the titular character becomes part of the efforts made to get two tortoises to mate because they're the last living tortoises of their kind. Eliza, who can talk to animals, introduces the two of them and gives them time alone. When she returns, she finds the male of the two biting the neck of the female. Mortified, she pushes him away from her and chides him for his actions. Not long after, she learns that biting is part of their mating rituals and essentially means they've accepted one another. She spends the rest of the episode trying to rectify her mistake.
- Plenty of dogs and cats that are kept for pets are known to gently nibble their owners to show their affection for them. Some birds do this too.