flatter
諛 centers on using words to please someone insincerely: flattering or speaking with excessive praise to gain favor.
諛 combines 言 (speech) with 臾, which likely contributes the sound and may relate to a sense of pulling or drawing in, suggesting speech that draws someone in through flattery.
The left side 言 is speech, and the right side 臾 looks like a person 人 holding something over a mortar 臼. Imagine someone using smooth words to grind down resistance: flattering speech that softens the listener.
For ユ, picture someone flattering you with exaggerated praise: "You are amazing!" The word "you" cues ユ, and the flattery is all about you.