Monstrous Personalities offers examples of non-combat encounters with monsters, creatures, and critters of the Dungeons and Dragons game.
Meifer is a lamia, and though she can be as bloodthirsty as the most evil of her kin, her thirst for knowledge of all things magical can make her a useful contact for a party of adventurers. Meifer makes her home in a town or city where she takes the form of a dark-haired human woman known publicly as a trader in spellbooks and other magic related tomes.
She inhabits small simple house made of stone. Her house consists of a single large room with seperate areas for cooking, dining, and sleeping. In one corner two massive bookshelves overflow with texts both mundane and magical.
If any of the characters find themselves in need of magical information, the locals refer them to Meifer. For a fee she’ll provide access to her library, but if any members of the party are spellcasters she’ll accept new spells as payment, working to expand her library. She might also offer to purchase tomes about magic. Meifer could become a recurring character, either purchasing magic related tomes from the characters, or sending them in search of a specific tome she desires.
If your players are not the type to attack on sight, you can drop some hint as to Meifer’s true heritage, the presence of a few beetles scampering along the floor, or the raspy sound of beetles scampering as she moves to pull a book from the shelves.
They might also find if they visit Meifer with some regularity that she sometimes has a servant present, likely someone she has enslaved, and perhaps plans on consuming, though of course she would never reveal these plans to the characters. If questioned she’ll simply refer to the servant as a mindless husk found wandering and who she hopes to rehabilitate.
Eventually the characters might discover Meifer’s true nature and find themselves forced to destroy her. They might also decide that her usefulness is enough to warrant ignoring her race and continuing to interact with her as they might any other contact. All this depends on the goals of the characters, and your campaign.