"Kat, why...when did you get here?" Charlie said, approaching her.

"I flew in about an hour ago, and I'm here for the geneticsseminar this weekend," Kat replied, "It's good to see you Charlie."

"It's great to see you, Kat," Charlie said, breaking out into a grin, "Why don't you come into my office?"

"I don't want to bother you," Kat said, "I'm sure I can come at another time."

"No, really, I insist," Charlie replied, taking her hand and pulling her with him, "Come on."

"Okay, okay, no need to be so pushy about it," Kat said, rolling her eyes.

The two walked back into Charlie's office. Larry, who had taken up Charlie's seat in front of the board, turned and looked at them. Standing up he walked over to Charlie.

"Hey, Larry, I'd like you to meet my friend Kat," Charlie said, pushing Kat forward, "Kat, this is Dr. Fleinhardt, he's a professor of physics at CalSci."

"Nice to meet you, Kat," Larry replied, holding out his hand.

"You, too, Dr. Fleinhardt," Kat replied, "I didn't know you knew Charlie."

"He used to be one of my professors," Charlie explained.

" Charles was one of my most apt students," Larry replied smiling.

"Well, you must be one killer of a professor," Kat said, "I just finished reading your paper on the eleven dimension gravity theory."

"Really?" Larry replied, genuinely suprised.

" Yeah, a few physicst friends of mine enjoy sending me mail. They've been trying to convince me that I should stop with the micro and go to the macro universe."

" I take it that your field is microbiology, then," Larry said, crossing his arms in a casual stance.

Kat nodded, "Actually, it's in genetics, but I've been studying changes in bacteria and fungi. I'm here for the seminar."

Suddenly a phone rang.

"That's mine," Charlie said, shuffling past Larry. Larry and Kat watched as the young mathematician riffled through his backpack. Pulling out a pile of papers, he haphazardly tossed them on the desk. Finally he pulled out a cellphone.

"Hello," he said, answering it, "Oh, hey, Don...Yeah, no problem...Are you sure?...Now. Don, I need to...okay, okay. I'll be down in a few minutes. Yeah, okay. Bye."

Hanging up he looked at Kat and Larry.

"I'll be right back," he said, hurriedly running out of the room.

Larry and Kat watched him go. Larry shook his head and walked back to the chalk board. Kat stared in the direction Charlie left for a moment longer.

Turning back to Larry she asked, "What was that all about?"

Larry looked at her and returned to leaning on his hands, staring at the chalkboard.

"Probably Don has some new case," he said, "I've told Charles that he's wasting his most ingenious years in helping the FBI..."

"Wait! Don's here! And he's working for the FBI!" Kat exclaimed.

Larry looked back, a confused expression on his face.

"Yes, he never left after..." he paused.

Kat nodded.

"I heard about their mom," she replied, "Cancer, right?"

Larry nodded. Kat sighed.

"I wish I had called," she said.

For a moment neither said anything. Finally Kat walked over to the desk and began organizing the papers Charlie had tossed onto the table. Larry watched, a little suprised, but didn't say anything. Suddenly Kat chuckled.

" I guess somethings never change," she said.

Catching Larry's expression she explained, "I used to help Charlie clean his locker at school because he could never find anything before class. It was an honest to God nightmare."

"So you and Charlie went to school together," Larry replied.

"Yeah," Kat said, "I used to live across the street from him. We were pretty good friends. Actually a little more than friends."

Larry tilted his head a little, looking at Kat expectantly.

"Oh, no. Nothing like that!" Kat immediately exclaimed, holding up her hands, "I mean we used to be like brother and sister."

"Would it be rude to ask what happened?" Larry replied, crossing his arms.

Kat laughed, "Not really. It's thesame thing that happens most of the time," She put down the neat paper pile, "We grew up. We went to school together for one year. Then Charlie went to Princeton. I graduated and..."

"The perils of youth played on," Larry finished, picking up a prism on Charlie's desk.

"Exactly," Kat replied.

Suddenly Charlie appeared in the doorway.

"Hey, Larry, is there a chance you can give me a ride to Don's office?" he said, sounding slightly frustrated.

"Sure, Charles," The older man replied, heading for the door.

Charlie looked over at Kat and said, "Want to come? Unless your busy or...," he looked at his watch.

"No, I've got time," Kat said, checking her watch, too, "The lecture isn't until tommorow morning. I was actually going to the hotel, but I can't pass up a trip to the Feds."

"Thanks," Charlie said. He waited for Kat to grab her purse.

The two of them and Larry walked out of the office and down to Larry's car. Larry drove while the two friends chatted in the back. Soon they were in front of Don's building.