Natsu tried walking around to find out who was following her, but the books boundary kept that from happening.

"Stupid book! The one time I actually need to get far away from you!" Natsu yelled, knowing that he could not be seen or heard by the follower.

"Natsu, over there." Lucy said, calmly pointing in one direction, even though her insides were shaking with fear.

They have the scent of a Heartfilia. I can see why she's so scared, but I don't like seeing her scared. Wait, what am I thinking?! Stop feeling sympathy Natsu! You are a demon! Even if there was a connection between us, I'm a demon, she's a human! Focus Natsu!

"That's helpful, now if only I could pass the boundary?" Natsu said.

"I'll walk up with you. They can't see or hear you, so you can just knock them out." Lucy whispered.

"Alright, but walk up casually, like you don't know that they're there."

Lucy obeyed and walked up as if nothing happened. She saw a flicker of movement from the side somewhere, but ignored it, knowing Natsu was following their every step.

"Go a little to the left." He instructed, Lucy following them precisely. When they got close enough, Natsu leaped onto the person, keeping them down, and the follower terrified and confused about what was holding them down.

"A Heartfilia guard!" Lucy merely spoke as she gasped.

"H-How are you doing this?! What's keeping me down?! What's going on?!" They yelled, looking behind them and seeing nothing, whereas Lucy saw Natsu holding him down. 

"I have something you could tell him. If word travels fast and gets to Fairy Tail, then you could be feared." Natsu smirked. Lucy liked this idea and repeated word for word what Natsu said, so that the guard hear. His eyes grew with fear as Natsu let him go.

"Go on and tell my father. He'll regret ever tracking me." Lucy finished, smirking herself.

With that, the guard was gone, and Natsu and Lucy now had a new goal.