She never even heard her coming.  Sara was fast and quiet and professional...and that caught Kate by surprise now.  She could've flinched when the Lieutenant walked in, telling her to ease off.  She actually [i]might've[/i] done, and there would've also been some kind of response that started with 'But...', [i]but[/i] that sort of died on her lips as she understood that she hadn't sleeped, hadn't rested, and hadn't done anything but work on this ever since she was presented with the evidence of Eren's current being.  It was too much, too quickly.  She couldn't put it down, at least...not until Sara reminded her that she was pushing too hard.  She thought that the seriousness of things would sharpen Eren's wits.  When things got serious, so did he, but...no.  Sara was right.  Kate gave her a quiet nod of understanding and backed away from the cell.  For a moment, she looked down, irritated with herself by the mistake she made, but then she heard Sara again and she sort of stared a moment.

[color=f7941d]Is she angry with me or...just trying to help?[/color]

No, there was just a hint of a smile.  She hadn't expected that.  Katherine started to return the smile, and then they both got back to the matter at hand.  Eren had not started any sort of shouting match or gotten belligerant when he was talking with Kate.  He probably wasn't going to start now, but one thing that he knew was that it wasn't likely that the Brunette was going to lie to him.  She might not have ever told a lie in her life, simply because she'd be bad at it.  Or rather, she wouldn't stand for it, because people not believing her when she spoke the truth of things was simply unacceptable to her.  So, Sara explained what was going on and...well, she must have known about their connection back where it all started in Shigenshina, since she introduced Kate to him.

When asked Sara moved on and asked his name, he hesitated only because he didn't know how to place this new woman, and then answered with his stance stiff and upright, [color=8dc73f]"Eren Jaeger, ma'am."[/color].  Kate remained silent, as her part in this was now essentially finished until she was asked some piece of information or she needed to interject something.  There was no rumor or information at all on how Sara Reinhardt interrogated people.  Usually, there wasn't anyone for a Titan-killer to question like this.  Kathering waited for the time in which she would be needed now.