Harry POV
The Death Eater was holding her strongly, and he wondered if he was somehow hurting her, but she did not complain. 'What's your name?' he asked, although he never knew if it was out of curiosity or just because he wanted to make her feel better 'My name is Katherine' she answered, sounding for the first time scared or was it bothered? He never knew that either.
But suddenly everything happened too fast, the death Eater attacked him with a Cruciatus curse and he dodged it gracefully the next second he was lying on the floor watching the guy hitting Katherine, hard, and he took his wand out of his jean's back pocket and screamed 'Stupefy'. Then the man stopped and fell to the ground with a thud sound. Katherine stared at him astonished; he was still holding his wand on his right hand.
Katherine POV
She had never seen a wizard using real magic with a real wand and was very surprised. She had to admit that from the perspective she had Harry was a hell of a good looking guy, with those deep green eyes. He looked as if she had discovered his most hidden secret, and a bit lost too. 'Are you alright?' he asked her 'I am'she said.
Harry POV
For a second he thought he might have deceived her but then she asked 'What is that you are holding?' shit, he was in trouble 'This?' he said showing her his wand. 'Yeah that. What happened to this man? And what the hell did you do to knock him like that?' He tried his last resort to trick her, 'I threw one of this and hit him in the head with it' he said not convincingly at all, for she said 'Yeah, because knocking someone out by throwing a wooden stick, is something you see in your everyday life, right?' she asked sarcastically, and he laughed "If she only knew…" he thought to himself. He struggled between telling her the truth or just erase her memories and let her go; but something was holding him, she had him absolutely charmed and he could not let go of her so easy.
Then they heard some steps and minutes after, Ron came into the room and saw the scene before he got time to answer. "Saved by the bell" he thought.
Katherine POV
The ginger-haired guy and Harry, told her to wait right where she was, but there was no way in hell that she was staying there to be interrogated or worse. So she escaped as soon as they stopped watching her, although she would have loved to see Harry get out of the I-saw-your-wand situation. She used the fire exit to leave the building and as if nothing had happened she went to a Costas Café to get some lunch. All the hostage-thing made her feel hungry, but it was too early to feed on a human and be unnoticed. So she contented herself with a sandwich and a coffee for the time being.