have (someone) under (one's) spell

To be extremely fascinating, enchanting, or seductive to someone, causing them to be under one's control or influence as a result. Our son has never acted out like this before. I think that new friend of his must have him under his spell. I would normally never rush into a relationship this quickly, but Susan has me completely under her spell. The duchess has had countless men under the spell of her incredible beauty and charm.