Flatterers in fiction

The ancient philosopher Plutarch wrote a famous essay on how to tell the difference between a friend and a flatterer. In this essay, he lists several qualities associated with a flatterer, including:
1. being inconsistent and willing to change into whatever seems most attractive to the victim;
2. appealing to the worst angels of the victim's nature and copying their vices rather than their virtues;
3. seeking to please the victim in the moment, even if it will cause the victim greater problems later on;
4. seeking to separate the victim from their real friends.

With this definition in mind, what are some examples of flatterers from fiction, particularly modern fiction? What traits, if any, do they and their victims have in common? Are there any stereotypes associated with fictional flatterers, either in terms of physical features or psychological makeup?