Yassen didn't like aquariums; there were too many civilians, too much CCTV, and a lot of enclosed spaces. But his orders were to eliminate his target here, so here he was. And it was a normal, term time Thursday afternoon; there weren't many children about, and those who were around were mostly babies or toddlers in pushchairs.

His target was Harold Williamson, an ordinary seeming banking executive, who funded some very unsavoury animal research. Yassen had been paid to kill him here, making a point about the conservatory programmes the aquarium had, to shine a light on his unethical dealings.

Ironically, his target was here for a business meeting. It was a meeting with his bank, but Yassen appreciated the irony all the same. He had been scoping out the aquarium for a week, entering daily with a different disguise, and had quickly decided how and where he would carry out the kill.

Underneath his jeans and sweater, he was wearing a business suit. His plan was to interrupt the meeting in the conference room, apologise and say that there was an urgent call for Mr Williamson, and then take him to one of the conservation classrooms before taking the shot.

"Ian!" Yassen was swiftly brought back to his surroundings by the slightly tearful sounding cry. Glancing around, he saw a small boy, who was looking around the 'Coral Kingdom' room, but had his back to him. The blond hair and the fact that he was looking for an 'Ian' was enough to pique Yassen's curiosity.

"Are you alright?" he asked in flawless and unaccented English. The boy turned around, and Yassen found himself looking and a child, probably about four years old, who could only be Alex Rider. He could see his father in his face.

"I can't find Ian," the boy replied.

"Who's Ian? Is he the person looking after you?" Yassen asked, knowing the answer even as Alex nodded his head. He thought for a moment. Williamson would be in his meeting all afternoon - there was no rush to murder him any time soon - and he had to admit that he was curious how the super spy had managed to lose his nephew in a not very busy public place. Alex hadn't said that he and Ian were related, but he didn't need to - Yassen already knew. Clearly small children could run away from anyone, even one of MI6's top field agents who had a much more acute sense of his surroundings than most other parents or guardians. He made his decision; he would help reunite Alex and Ian and then kill the banker later in the afternoon.

The thought occurred to him that he could just take Alex with him, back to Scorpia. He was sure that they would like that - the chance to mould Hunter's child into a killer from such a young age. He would be the perfect secret weapon. But as quickly as the thought occurred to him, he had dismissed it. They weren't his orders, and so much of Alex's childhood had been stolen from him. Yassen wouldn't be the reason that Alex Rider became a killer. He would never have done that to John. He had met Ian a few times on missions too, and they had always shared an uneasy truce, neither one taking the first shot.

All of these thoughts had crossed Yassen's mind impossibly fast, and less than a second had passed since his last question.

"And where did you last see Ian?" he asked now.

The boy thought for a moment. "We were in the shark tunnel. And I thought he came in here, but he's not."

"I see. Shall we take a wander around and see if we can find him?" Alex nodded. "And what's your name?" Yassen asked. "My name's Thomas," he added.

"Nice to meet you, I'm Alex." Polite, even though he was lost and probably scared, Yassen noted. Ian had made sure that Alex's manners were up to scratch. They walked through the different indoor exhibits, stopping frequently as Alex became distracted by the different animals they came across. It was approaching half an hour since Alex had lost Ian when Yassen heard the call of "Alex" in the distance.

"Does that sound like Ian?" he asked, knowing before Alex answered that it was indeed Ian calling.

"Yes!" Alex said excitedly, and began looking around him, clearly disappointed when he didn't see Ian.

"I think it's coming from that direction," he said pointing back towards the shark tunnel. "Come on."

The two of them walked back towards the shark tunnel, and Yassen was surprised when Alex slipped his hand into his own. They reached it in a couple of minutes, and Yassen saw Ian speaking to one of the aquarium guards, obviously reporting Alex's disappearance.

"Ian!" Alex exclaimed, now relinquishing his grip on Yassen's hand and running towards his uncle.

"Alex!" Ian sighed in relief and Yassen saw the tell-tale bulge of a gun as he bent down to pick his nephew up into a big hug. Was he working? Had he deliberately left Alex alone in the shark tunnel? "How many times have I told you not to wander off? I was so worried!"

"I'm sorry Ian," Alex whispered, but it wasn't very quiet and Yassen heard him from half way down the tunnel. "I couldn't find you."

As though for the first time, but Yassen was sure that Ian had clocked him the second that he and Alex came in, Ian looked up and their eyes locked. Ian recognised him instantly, even with the latex mask that he was wearing. Yassen could tell from his expression.

"Thank you so much for looking after him," he said.

"It was my pleasure," Yassen replied, not completely lying. The guard that Ian had been speaking to, seeing that he was no longer needed, began to walk away.

"Thank you," Ian said, turning to him as he left. And then turning back to Yassen, "please, let me buy you a coffee to say thank you," Ian said and Yassen knew that he wasn't being given an option.

"That's really, not necessary," he said anyway, but Ian insisted. "Alright then, thank you."

As the three of them walked out of the shark tunnel and back above ground, Yassen wondered whether Ian really was working and had deliberately left Alex alone, or whether it truly had all been an accident. Ian deftly steered them towards one of the themed cafés and got them a table in a corner where they wouldn't be overheard and no one would be able to sneak up behind them.

"Would you like a hot chocolate, Alex?" Ian asked.

His eyes opened wide in excitement and he nodded enthusiastically. "Yes please!"

"And what can I get for you, Thomas?"

Yassen thought for a moment. The sensible thing, when being offered a drink from an 'enemy' would be to get a sealed drink, maybe a bottle of water, if he got anything at all, but he had never considered Ian to be an enemy.

"I'll have a decaf cappuccino please."

Ian raised his eyebrow in a gesture of surprise. Except it wasn't surprise; it was more subtle than that. He left to join the short queue at the till to get their drinks, leaving Yassen alone with Alex, once again.

"So what was your favourite animal that you saw today?" he asked.

"I like the sharks!" Alex said excitedly. "Did you know that the great white shark can see up to eight metres away, even if it's pitch black? And did you know that a group of sharks is called a shiver? "

"I didn't," Yassen said. He was lying, but he didn't want to quash Alex's enthusiasm. He spouted some more interesting-if-you're-a-four-year-old facts for a couple of minutes. "I've got some other shark facts if you're interested?"

Alex gasped. "Yes please!" Yassen smiled, and not only to keep his cover. He genuinely liked Alex. It was just a shame that they would probably never meet again after today.

"A shark's nose is called a snout, and there are receptors that detect electrical currents. It's like an extra sense that they have."

"Wow! So can they hear the light bulbs and things in the aquarium?" Alex asked interestedly.

"It's not quite that they can hear them, but yes they can probably sense the electric circuits around the tank."

"That's cool! Have you got any more shark facts?"

"They can smell one drop of blood in twenty-five gallons of water. That's about the same as a teaspoon of blood in a swimming pool."

"Wow! That's not a lot of blood!"

Just then, Ian came back carrying a tray with their drinks and a couple of muffins. A triple chocolate chip one and the other looked like blueberry.

"What are you two talking about?" Ian asked as he sat down.

"We're talking about sharks! Did you know that they can smell a teaspoon of blood in a swimming pool?"

"Wow!" Ian said in the tone of voice you use when a child is excitedly telling you something you already know, but you don't want to discourage them. "Would you like to do some colouring Alex? I picked this up from the counter-" he said, pulling an aquarium themed colouring booklet from under the tray, "-or I've got a Thomas the Tank Engine colouring book in my bag."

"I want to colour the sharks!" Alex replied excitedly. "Please," he added after a look from Ian, who placed the booklet in front of him.

"There you go. And here's your hot chocolate, little man."

"Thank you!" Alex said as he eagerly reached for the mug.

"Careful, it's hot," Ian warned, putting it down on the table instead of letting Alex take the mug from him. Alex was now eyeing up the muffins on the tray.

"Yes half of it's for you," Ian laughed as he split the triple chocolate muffin unequally in two, putting the smaller piece on a spare plate which he gave to Alex. Then he picked up Yassen's cappuccino and the blueberry muffin and placed them on the table in front of him, before picking up his own drink (it looked like a latte to Yassen) and putting the tray in front of the spare chair on the table.

"Thanks," Yassen said.

"No problem. Thank you again for watching him."

"It was no bother." Yassen almost wanted to laugh at the politeness that they were exuding as though they were strangers, not people who had definitely held each other at gunpoint and tended the others wounds on more than one occasion, but he didn't; he just sat quietly and waited.

After a couple of minutes, Alex had finished his muffin and Ian had tested the temperature of the hot chocolate; it was now cool enough for Alex to drink safely. He looked up at Yassen, with chocolate from both his muffin and his drink smeared around his mouth, and grinned.

"Do you know any more shark facts?" he asked cheekily as he sipped at his hot chocolate again.

"Let me think," he said, taking a sip of his cappuccino. "They don't have any bones."

"Aren't teeth bones?" Alex asked quizzically.

"Technically no," Ian informed him. "Do you want to do your colouring?"

"Okay," Alex said. Clearly he was used to Ian directing him to do something when he wanted to stop conversations, because he didn't complain, but finished the last dregs of his hot chocolate and then set to work examining his colours and the pictures he had.

Once Alex was settled into colouring and paying them no attention whatsoever, Ian and Yassen began to talk.

"Why doesn't he call you 'Uncle Ian?'?" Yassen asked.

Ian sighed. "If anyone didn't know about our connection but overheard Alex calling me his uncle, it could be used against me. He could become a target, and I don't want to put him in more danger than he already is."

"So leaving him alone in the aquarium today was..?"

"Unfortunate. My sitter bailed," he explained, "and you know that in my line of work I can't exactly take unexpected time off. But he was being watched on the security cameras so I knew where he was the whole time."

"And why are you here?" Ian just gave him a pointed look in reply.

"I've answered two questions. Now it's your turn."

Yassen had known that this would be coming, but waited until Ian actually asked him a question. He wasn't going to give up any information that he didn't have to.

"Your target?"

"Harold Williamson." Ian nodded as though Yassen's answer was what he had expected.

"Elimination?"

Yassen nodded. But before they could continue their conversation, Alex looked up from his colouring.

"Ian look, it's a great white!"

"Ahh good job, buddy! Do you know what scientists call them?" Alex shook his head. "Carcharodon carcharias."

Alex looked like he was turning the words over in his mind. "Carch…"

"Aro…don" Ian supplied, sounding out the different syllables.

"Carcharodon… carch…"

"Ari… as."

"Carcharodon carcharias?" Alex said tentatively, with Ian and Yassen smiling their encouragement.

"That's it! Good job!"

"Carcharodon carcharias," Alex said more confidently this time, before smiling and getting back to his colouring.

In the meantime, Yassen had finished his coffee. He had not touched the muffin.

"Thank you for the drink," he said, standing up. "I really must be going now, but it was lovely to meet you both." Alex's interruption had been a welcome respite from the subtle interrogation that he had known would be coming from the moment Ian invited him to have a drink. And now seemed like a good time to escape. Ian knew his target and that was more than enough for Yassen's liking. If he had already completed his assignment, he would not have minded staying with Ian and Alex for the afternoon, but as it was he had a job to do.

Ian was standing up too. "Thank you again," he said holding out his hand. If it were anyone else, Yassen would have made an excuse to avoid shaking it, but it was Ian so the usual self-preservation rules didn't apply.

"You're welcome," he said taking his hand politely. He felt a piece of paper that Ian was surreptitiously handing to him and palmed it, giving him a knowing look.

"It was nice to meet you, Alex," he said, ruffling his blond hair. "Try not to wander off again."

"It was nice to meet you too," he said politely, looking up from his colouring. "Thank you for teaching me cool shark facts!"

"You're very welcome. The exhibits have interesting facts about all of the animals in them if you want to learn more." He smiled seeing Alex's wide eyes at the thought of learning more about sharks. "Have a good afternoon," he said before finally making his way out of the café.

Once he was in a secluded spot, away from any CCTV, he looked at the piece of paper that Ian had given him.

'Call me if you ever need anything' he had written, followed by his phone number.

Yassen had unintentionally memorised Ian's number in the couple of seconds that he had been looking at it, and quickly ate it to destroy the evidence, before setting off to complete his mission.