Dialogue needed and more improvements!?

[Maddison]

My two protagonist's first meet in the girls house. It's late at night and she goes into her study she walks around a little studying the books on the shelves when she notices one is missing.

she wanders back to the door when she hears a boy talking.

she turns around to see him sitting near the window reading from the book.she freaks out and shouts at him to leave and get out.

he smiles at her and puts the book back.

then approaches her. he keeps moving closer to her and pushes her up against the bookcase.

he sees her face and then stops.

then I need some dialogue please help!

 

[lottie]

The sky was dark outside, Katie couldn't sleep. Stretching her arms she pulled her slippers on and wandered down to her study. With her delicate finger, she ran it along the many books, spread along the vast bookcase. Suddenly she stopped; she noticed one is missing. Thinking nothing of it she decided to go back to bed.
Katie was stopped when a voice said, "Nice book!"
She turned on her heels to see a young boy sitting near the partly open window. The curtains fluttered in the light breeze.
"GET OUT!" Katie screamed at him, "Get out of my house!"
The boy merely smiled at Katie and put the book back on the shelve. He then approached her slowly. Step by step, he got closer to Katie until she is pushed against the bookcase.
He saw her beautiful face, highlighted in the moon light and stopped.
"What are you doing here?" Katie asked him. "Who are you? How did you get in?"
The boy chuckled, "So many questions, so little time!"
"What are you talking about?" Katie demanded.
The boy tapped the side of his nose "Wouldn't you like to know!"
"Leave!"
"What if I don't want to?"
"I'll make you!"
"How will you do that?"
"I'll find a way," snapped Katie trying to sound tough.