high, steep
隗 centers on a steep, towering height, like a high cliff or a lofty, imposing figure. The idea of being high and steep connects both the physical and metaphorical senses.
隗 combines ⻖ (hill, mound) with 鬼, which likely contributes the sound. The hill radical suggests a steep, elevated landform, while 鬼 may have originally depicted a tall, imposing figure, reinforcing the idea of height.
A steep hill (⻖) with a towering demon (鬼) on top: the demon makes the hill seem even higher and more imposing.
For カイ, imagine a kite (カイト) soaring high above the steep hill, its string held by the demon: kite -> カイ.