Katherine raised her brows as an argument between Fil and Leem escalated. She was beginning to wonder if they were going stir crazy protecting her while she worked. Three days they had accompianied her to Cambridge to watch her sit and mull numbers.

"Nah, it's one over 'x', so if our previous result works out ta point eight then the reciprocal is one point two-five," Fil growled.

Leem tapped the portable whiteboard they stood in front so furiously with his marker that it slowly rolled away from him. "We already did our division back here so we don't need a flip it. The answer is just zero point eight."

In an attempt to keep the brothers Coley occupied while she worked, Katherine had jotted down a few equations on their board and challenged them to have a go while she used the room's large projector screen to analyze her data. One of the techniques that helped her sort out patterns was to put herself back into student mode and look at everything in large format. Of course, this was a lot more effective when there wasn't a pair of bull-headed, Brummie brothers trying to prove which of them was smarter on one side of the lecture hall stage.

Finally, after failing to convince Leem of where he'd gone wrong, Fil turned to her in exasperation and shook his hands at the heavens.

"Dr. Adams, I'm right," he stated dramatically. "Could ya just tell him I'm right? I know my maths."

Katherine tried not to laugh at the expressions on their faces as she looked down at them from her seat half-way up the auditorium. She felt a bit guilty for their frustrated state. They had both discarded the blazers and rolled up their sleeves. Fil had kicked his shoes aside while Leem had loosened and flipped his black tie over his shoulder They were ridiculously cute, the pair of them, and in the last few days she had learned that they were both bloody brilliant. Every time she wrote a new problem on the board, she had increased its difficulty. Neither of them had been all that challenged by concepts that would have sent some of her better students around the bend.

"I'll inform you of who is right, but first you have to tell me where you two received your degrees," she replied.

They looked at one another in confusion. Fil folded his arms and poked his lips out while Leem rubbed a hand over his head.

"W-We didn't go ta college," Fil stuttered and glanced sideways to Leem. "Is she making fun of us?"

"Nah, she just wants ta know how we know how to do this stuff."

Katherine squinted down at them. "You've taken courses, then? I mean, a person cannot just know these kinds of things. That problem you are about to solve is one of my weeklies. You would have to have studied some pretty advanced math to work your way through it this far."

Fil frowned. "What's a weekly?"

Katherine smiled. "It's an optional assignment I give my students each week to work on if they're up to the challenge. Only a handful of them attempt the problems, one or two might actually turn in an answer. Fil, you've practically solved this one in under an hour. Sorry, Leem, you were close but he was right about that last inverse function."

Leem cursed and threw the marker down on the white board's ledge. "Damn, I thought I had 'im."

Fil smiled and twitched his brow. "I told you."

Katherine cleared her throat. "So? Spill it? Your education?"

Fil shrugged. "When ya go into MI6 training early like we did, they make ya do all manner of tests and try to figure out what you're best at. Leem's good wit languages so they sent him undercover to a lot o' places so he could learn the accents. I'm good at reading people so I did a lot of psychology courses. We were both sent to France for a bit and studied with this fellow named Rene Prurard but when they saw I was the one better wit numbers, I was conscripted to compile statistics and do analysis of surveillance data. It's boring as shite so I didn't last long in that position."

Katherine blinked rapidly. "Rene Prurard? Are you serious? He's only one of the greatest minds in French mathematics."

She looked between them.

"If you have these sorts of talents, why aren't you both in intelligence full time?"

Leem and Fil looked at each other and smirked as if in on a joke. Leem glanced back up at her with a boyish grin. Every time he looked at her that way, her heart skipped a beat. He was too handsome.

"We tend ta get in trouble. Problems with authority and such," he said with a shrug.

Fil nodded. "Yeah, that, and we also tested a lot higher in a different area."

She crooked a brow. "What's that?"

Leem's voice dropped an octave. "Combat."

She held her breath a moment. The man could send shivers up her spine with just the right inflection in his voice. His features darkened then and he looked at Fil. It was as if a switch flipped in his head and he lost all his good humor.

"I'm going to use the facilities," he said quickly. "Take care of the doctor."

Katherine frowned as she followed his hasty departure with her gaze. She rubbed her lips together to prevent a frown. He didn't call her Kat anymore. She had become 'the doctor' or 'Dr. Adams'. He had been all business since they'd returned to Cambridge.

"Don't take it personally, Dr. Adams," a deep voice commented.

Her eyes returned to Fil anxiously. "Wh-What?"

"I'm sorry he's been standoffish," Fil said hesitantly. "I –ah – might 'ave had something to do with that."

Katherine's face heated. "I, um, . . . what?"

"I gave him shit about you," Fil admitted. "Said he shouldn't be messing around. Told 'im it was unprofessional."

She looked away to conceal her expression. Her face burned. Guilt punched her in the abdomen.

"I-I don't see why you should apologize to me for anything. It's none of my business what you and he discuss."

She heard Fil shuffle around and glanced back down to see him putting on his shoes and blazer. He adjusted his cuffs with a contemplative expression.

"Well, I just thought you should know. I see you're sad sometimes when you look at 'im and I feel bad about that."

Katherine didn't know how to respond. The whole thing was a bit too much of a roller coaster. She swallowed.

"You can make it up, Fil," she smiled sadly. "Come up here, sit next to me, and tell me what you see. I need a fresh pair of eyes on this."

She found herself unable to concentrate thinking about Leem. The figures and numbers she had placed in the document camera to project on the screen were beginning to all blur together. Fil just might be able to help.

His eyes rounded. "My eyes?"

"Yes, yours! You know your 'maths', right?"

Fil's face deepened from a pink to crimson. "Not as well as you."

She smirked. "I should hope not, otherwise I'll be out of a job."

So, Fil took the seat next to her but stretched his feet out into the aisle. He was a bit larger than Leem, definitely an inch taller and somewhat broader in the shoulders. He had the same colour eyes, that sort of dark, greyish green, but his gaze was softer and less world-weary than his brother's.

"So, what am I lookin' at?" He asked as he tried to make himself comfortable.

"I don't know," she murmured as she returned to analyzing her computations. "What does it look like to you?"

"Um, give me a minute," he chuckled. "There's a lot up there."

Each of them stared silently at the screen, pouring over her work. Several minutes later, Fil sat forward.

"What do you see?" She asked.

He shook his head and narrowed his eyes in thought. "Strings."

"Strings?"

"It looks like one of the puzzles you gave us about the strings. The one about predicting the length of strings randomly cut from two rolls. That was a hard one. This mess seems as if it uses the same methodology."

Katherine scanned back over the algorithms behind the latest encryption she had cracked. Some very disconcerting realizations began to form.

"No," she muttered.

Fil coughed. "No? Shite, I shouldn't have said anything."

She chewed her lip. "Oh, crap, that's not what I meant. You're not entirely wrong. This follows that very closely, too closely. It's been modified to mask it but you're right in a way, it's that puzzle with a few twists.

A shiver coursed up her spine. She and her mentor had developed some of these problems together. In fact, the strings puzzle was his favorite. What had been hidden before her very eyes made her sick to her stomach. She turned to back to Fil. If what she suspected were true, things may not be what they seem.

"Can Mycroft be trusted?" Her eyes felt too large for her sockets.

Fil frowned. "What do you mean?"

"I-I just don't know him like you do. Can he be duplicitous? Would he betray his country?"

"No," Fil responded adamantly. "No, Mycroft loves England. I don't think there's anything else in the world he loves more. Um, well, maybe one thing. . ."

Katherine studied his face. "Truly? You and Leem think he's trustworthy? You've never had any doubts?"

He gave just the barest dip of his chin. "No doubts, Dr. Adams. He'd never admit this, but he's like . . . an uncle to me and Leem. He was the one who recruited us. He saved us from the street after our Mum died. Without 'im, who knows where we'd be."

She stood up. She didn't need any more reassurance. His endorsement was good enough for her.

"We have to go speak to him then."

"Right now?"

She nodded swiftly and looked around anxiously. "Yes, let's get Leem and get out of here."

Katherine and Fill packed up her things and shut down the projector equipment. She grabbed Leem's blazer and slung it over her arm. Then, she hurried towards the exit. Fil leapt in front of her and yanked it open. She grinned at him, stepped into the hall and stopped in her tracks when she saw Leem with Mycroft's assistant at the end of the corridor.

"Oh, hell," Fil muttered under his breath.

Katherine blinked and squinted as she tried to wrap her head around what she gazed upon. Leem had back against the wall with Anthea practically pressed up along his entire length. His tie was in her grasp and she was in the process of tugging it back into place as she looked up at him with her signature knowing smile. Katherine watched, dumbstruck a moment, until Anthea closed the space between them and kissed him on the cheek in a sort of lingering manner. Katherine's breath caught in her throat. A bubble of pain formed in her chest. Leem had such a tender look on his face.

"I am so relieved to see that you're alright," Anthea murmured. "I was worried."

"Were you?" Leem mumbled.

"Of course."

"Well, you don't have ta worry about me, Thea," he returned in a low voice. "You know it takes more than a graze to knock me down."

"Mm hmm, yes, I do know."

Leem laughed. "Where's the boss? He can't be far behind. You're going ta get yourself into trouble."

"Oh, I hope so."

It was as if they existed in their own little vacuum. Katherine spun quickly, not wanting to witness anymore and slipped back into the lecture hall. Fil followed.

"Dr. Adams, um," he grimaced. "Yeah, see . . ."

She knew her face had to be pale. It felt at once both warm and cold.

"It's none of my business," she whispered shakily.

"But it's nothing," Fil stammered. "I mean, it's not exactly nothin'. Leem's been in love with her forever. Um, shite, forget that. What I meant was, that nothing's ever come of it. She strings him along ta piss off Mycroft."

Katherine looked down at Leem's blazer that she still gripped tightly. "He's still in love with her?"

Fil rubbed his temples as if struck by a sudden headache. "I was just talking out of my ass, Dr. Adams. I don't know for sure."

She slung the blazer over a nearby seat. "Doesn't matter. It's none of my business. None."

Fil groaned. "He likes you, though. Don't be mad at him."

Even though her heart was breaking, she wasn't mad at Leem. He couldn't help that he was in love with someone else. Her face flushed again. All this time she had fooled herself into thinking their connection was something special. She'd blamed her situation from preventing anything more from developing between them. Turns out, she never had a chance.

Leem was already in love with someone else.