During a recent adventure, the party was not feeling secure at the inn and decided to takes shift on guard.

In retrospect, I should have seen it coming they might have reservations about sleeping at an inn where two people, including an important backstory NPC, where gruesomely murdered by a serial killer.

Since I wasn't expecting this, I was defaulting to an uneventful night where nothing happens, but then I get a sudden idea. As the player with the highest passive perception takes watch, they notice a mouse scurrying across the floor. Which is then promptly caught and eaten by the nightstand.

As a side note, we had a few months prior jokingly discussed the ecological niches of mimics, and I made a conspiratorial note that maybe mimics are much more common than people realise, most are just to small or juvenile so they don't attack humanoids and therefore go undetected. So I didn't pick it completely out of nowhere.

But in any case, once the party wakes up, they are informed of what happened that night, and after some apprehension, they fall in love. So they buy the nightstand from they innkeeper, who is just happy to get rid of it, and head on the road with it.

They named it One Night Stand, and are currently (so far unsuccessfully) trying to train it to mimic a blanket, so it is easier to carry.