fall under someone's spell
1. Lit. to come under the magical control of a magician or similar person. The damsel fell under the wizard's spell and sat there speechless. As the children fell under the witch's spell, they went to sleep.
2. Fig. to be fascinated by someone; to be enchanted by someone. She was so beautiful. I fell under her spell at once. Wally fell under Donna's spell and became helpless in her presence.