New ideas don't just appear. They are the result of conscious, or subconscious, connections being made by the creator. Someone took two or more disparate ideas and combined them to get an unexpected result. Concept artists use this strategy all the time. Need a cute dragon? Combine a dragon with something soft and fuzzy, maybe a peach or a puppy, and start illustrating. I call this the Idea Matrix.
The initial idea will probably evolve once pen hits paper but you're just looking for something to get the creative juices flowing.
Here's how it works: I write down the thing I'm designing (character, logo, UI, etc). Then I'll list the qualities I want this thing to have. Following that I'll list other things in the universe that have those qualities. Once I have a list of those things I'll select my favorites and begin exploring combinations of the intitial concept with new references that represent more emotional associations. Try it out!