Man I love kelpies. Like the rest of the sidhe, they're pretty fickle and can be helpful or terrifying. They could choose to bring you somewhere useful and help you out, take you on a wild joyride or just straight up murder you by dragging you down under the water where they come from.

I used to watch out for them when I was a kid because if one approached me offered me a ride, I'd sure as hell have taken it, I considered it worth the risk lol