Tell her the truth

Ashley thought carefully about how to phrase her power without having to make an actual statement. "Is there anyone at this school," she said at last, "who can control people?"

Jean smiled. "There are a few telepaths." she said, her mouth never moving from its smile, never opening, as Ashley clearly heard the words. Her draw dropped open. "And I'm one of them."

"You can- can you really control people?"

"Yes, although I generally don't use that much, outside of giving people a little nudge once in a while. For instance, if I need to speak to a mutant who hasn't told her parents what she is, I might use my power to get her mother to leave us alone and go do something else." She was talking about Ashley's mom, she realized. "I take it you have a similar power?"

"What if I told you that whenever I say something, anyone who hears me believes it?" she said as fast as possible.

Jean switched back to speaking aloud. "You mean that your powers are verbal in nature? That is what you mean right? You're trying to avoid using them, but that's your power?"

Ashley nodded, and Jean fell into thought.

After a moment, she said, "I've got an idea. I can use my powers to create a telepathic link between us that allows for two-way communication. There's a good chance that doing that will allow you to say things without using your powers, because they won't be spoken."

Ashley blinked, it sounded too good to be true. "Would that work?"

"Only one way to find out." Jean pointed out.