Saturday morning brought an expected knock on my door as Tobi and I were cleaning the house together.

"Ready for your first test?" I asked him, knowing we'd need to behave as a custodian and Katki would, just like we'd been practising throughout the week.

"Yeah," Tobi nodded as we both hurried to our respective positions.

I nodded when I saw he was ready and tried to hide my nerves as I entered the porch.

"Hi!" I greeted my friends enthusiastically when I opened the door to find Seren and Peter outside. "Come on in. What brings you over?"

The couple did as I asked, removing their shoes in the doorway as they entered.

"I remembered you said you were redecorating," Seren explained. "We wondered if we could help."

"Not in your state," I jested, pointing to her belly.

"I'm pregnant, not incapable," she scolded me, rolling her eyes as she and Peter walked into the lounge. "I can still help in other ways, like painting."

"Although, it looks like you've changed your mind?" Peter said as he observed that the lounge was back to the way it had been previously.

"Something like that," I concurred. "Do you guys want a drink of something? Herbal tea?"

"Sure," Seren nodded with a puzzled look on her face as she no doubt tried to figure out why I'd backtracked on the home improvements.

"Seven Zero Eight One," I turned to face Tobi, who played his impassive part well. "Please could you prepare four herbal teas? We'll drink them in here."

Tobi disappeared into the kitchen to do as I'd just requested.

"So, why the change of heart?" asked Seren as she sat down on the couch with her husband.

"A week wasn't really long enough for what I wanted in the end," I replied, hoping it was suitably vague.

"You should have told us," Seren insisted. "We might have been able to help."

"While working full time?" I raised an eyebrow and perched on the small desk chair. "It's fine, really, I just ended up getting distracted. I'll do it another time."

Tobi returned with the herbal teas on a tray. After he shared them out, I told him to sit in the armchair. I could tell from Seren's expression that she was surprised I let him take the more comfortable seat, but she said nothing.

Viewing Tobi from my peripheral vision, I could see he was doing a convincing job of being under the influence of the Ravim while the rest of us chatted.

Meanwhile, Tiger was in the mood for some games with her new friend and was clearly set on trying to get Tobi's attention. She started by climbing onto his lap, but after he successfully ignored her, she decided to paw at him and meow.

Seren joked that the cat seemed quite taken with my new house guest, and despite laughing along with her, I could see that Tiger was intent on making Tobi's first proper assignment difficult for him. I wanted to offer the blond man some words of encouragement, but I knew I just had to swallow them back and let him deal with the situation.

The conversation returned to more conventional chatter, but my feline was in a somewhat determined mood. She wandered over to the sofa for some fuss, but with our new guests deep in conversation, she gave up and returned to Tobi again shortly afterwards. I understood her reasoning – Tobi never usually said 'no' to her, and so her expectations had been set by his previous behaviour.

Having concluded that she wasn't going to attract Tobi's attention any other way, she hopped up on the little table next to him that contained his tea and a couple of ornaments, including a photograph of me with my parents.

When she was a kitten, she used to get my attention by knocking objects from the tops of tables because she knew I'd come running. So, I predicted what she was going to do a second before she did it, but it was still too late to stop her.

Looking at Tobi quite deliberately, she sat down on the table next to the framed photograph and pushed it over the edge with her paw.

Instinctively, Tobi reached out and caught it, replacing it quickly and resuming his stolid position.

It was a reflex reaction, and while he hadn't done it intentionally, it wasn't something a Katki under the influence of the Ravim would have done. With the potent drug flowing through their system, and without an instruction to tell them otherwise, an archetypal Katki would have just let the decoration fall and smash.

And everybody in the room knew it.

Seren was on her feet immediately.

"Did you see that?" she asked, her voice panicked and eyes wide. "Matty ... your Katki ... he just ..."

Tobi remained unresponsive, despite my friend's reaction. I was impressed that he'd made the decision to continue with the charade at this point.

"Seren, calm down," I responded in an attempt to pacify her, automatically standing up in case anything got out of hand.

"But ... that's ..." she tried, clearly rattled by what she'd just seen. "Peter, did you see that?" she pointed to Tobi but stared meaningfully at her husband. "That's not possible, is it?"

Peter sat still for a few seconds, watching Tobi, understandably trying to make sense of what he'd just witnessed.

"Something's not right," he agreed, also standing. "Matty, what's going on?" he added, facing me with the most serious expression I've ever seen him wear.

Feeling somewhat defeated, I sat back down with my head in my hands and sighed. I knew I hadn't acted as alarmed as I probably should have done when Tobi had caught the photograph. My head couldn't come up with a sensible explanation for what had happened. Besides, I didn't want to lie to my best friends, especially now that they suspected something.

But the alternative was to tell them what I'd done. A shiver of fear ran down my spine at the thought. If I told them the truth, and they reported me to the Andekas, my entire life would be over.

I fought back the anxiety and tried to think logically. This was Seren and Peter. I'd practically grown up with them. If anyone would understand my desire to help the Katki, it would be Seren. Peter was the most supportive husband in the universe. And they were my friends. They wouldn't report me, surely?

I looked up at them both. Their uneasy expressions told me they were waiting for my response. It had only been a few seconds since Peter had asked his question, but it had felt like an eternity.

Seren must have seen something in the expression I now wore, because she spoke before I did.

"You did something to the Ravim, didn't you?" she asked.

Knowing I was a scientist that cared about the Katki, she'd started to put some of the pieces together on her own.

"No," I assured her, before inhaling deeply. It was confession time. "I just ... never gave him any."

Seren's face filled with shock, and a second later, she took a step further away from the porcelain angel. Also looking stunned, Peter slid between her and Tobi protectively.

"Matty!" she cried as she edged away. "What were you thinking?"

"I wouldn't have invited you into my home if I thought there was any risk," I implored, standing up and gesticulating to the Katki. "This is the same man that just brought you your tea. Nothing has changed since you came in."

That fact seemed to catch her attention. Looking at me cautiously, she appeared to be working through the events of today more logically in her own mind.

"So, he's still doing what you tell him to? Even without the drug?" she reasoned.

"Well, sort of," I replied. "He's doing it voluntarily. Because he wants to."

Seren didn't look convinced, presumably partly because the blond man was still making an effort to act as he had been previously, despite the fact that Tiger was still pawing at him and we were all discussing his behaviour.

"See for yourself," I suggested. "Ask him."

Seren looked from me to Tobi and back again. Peter kept his eyes firmly on the Katki, his priority understandably being to protect his wife and unborn child.

After nobody spoke for a while, I broke the silence.

"Tobi, did I force you to do any of this today?"

The platinum blond's stance immediately changed once he interpreted my direct question as permission to drop the charade. Starting to pet cat that had so desperately being trying to get his attention, he shook his head.

"Matty isn't forcing me to do anything," he confirmed to our guests. "I got your tea because I don't want to go back to the Kinnisvara. So, I know I need to try to blend in and behave as people expect me to."

Seren's eyes opened wider than I've ever seen them after Tobi spoke.

"You want to ... blend in?" she asked incredulously, before turning back to address me. "And you ... you know his name?"

Taking a couple of steps closer to her, I took her hands in both of mine. The cat was sprawled lazily across Tobi, thoroughly enjoying the physical affection he was now showing her.

"I gave him a name because I didn't like referring to him as a number," I explained.

Seren was still looking apprehensive, and I couldn't blame her after everything we'd been told about this offshoot of society. Having always been warned that they were violent and uncontrollable, being faced with evidence to the contrary was probably quite a lot to process.

"Look at him," I added, appealing to her to consider what she was observing, rather than what she'd heard. "He plays with Tiger like that all the time. He's helpful and kind and likes to read and draw pictures. He's not what I expected, Seren. Don't judge him on anything except what you see in front of you. Please."

It was then that Peter started to walk towards Tobi, and I knew him well enough to understand what he was doing.

Peter had been spending his time sizing up the Katki, and ascertained, as I had, that he could overpower the slender man if he needed to. If Tobi was going to get aggressive, Peter would rather it was with him than with Seren, and he was testing the water before his wife did.

Stopping at the edge of the armchair, Peter slowly bent his knees so that he was balancing on the balls of his feet, with his head level below Tobi's, and I knew this was so that the Katki didn't feel threatened. Peter knew that his height and physique could make him appear intimidating, and he wasn't intending to start a fight. Reaching out his hand, but being careful not to touch the blond man, he started to join in with petting the cat.

"Tobi, right?" Peter asked gently, and Tobi nodded timidly in response. "It seems we never got formally introduced. I'm Peter, and over there is my wife, Seren. I'd like to apologise for our lack of manners today, Tobi. We've never met a Katki properly before, and you kind of took us by surprise."

Tobi looked up at Peter shyly, before his concerned gaze moved to meet mine. Assuming he wanted some reassurance that conversing with Peter would be all right, I smiled and nodded in encouragement. Having seen my reaction, Tobi's sky-blue eyes moved back to Peter, and he lifted the corners of his mouth just a little.

"Tiger seems to like you," Peter continued as he tried a different approach. "You like animals?"

"I think so," the porcelain angel replied as he continued to make a fuss of the cat. "I like this one."

"I like this one too," said Peter softly.

I turned to Seren, hope welling in my chest that my friends may leave their prejudice behind and accept this man without his medication.

"Can I show you a picture he drew?" I asked her.

Her confused brown eyes turned to me, and she gave me a small nod.

Letting go of her hand, I fumbled around in the paperwork on the bookshelf, finding the picture of Tiger that Tobi had drawn on the back of an envelope and bringing it back to her. Holding it out to her like a proud parent, I pointed to the pencil sketch and smiled.

"He did this without the Ravim," I told her.

Staring at it for a few moments, it seemed Seren was still trying to take it all in.

"It's good," she admitted, looking back at me.

"Can I see?" Peter requested without moving from his spot next to the chair.

"Sure," I replied and took it over to him.

Peter thanked me as I handed him the envelope and he studied it.

"You're clearly very talented," he told Tobi after a few seconds. "How long has it been since the Ravim wore off? Do you know?"

"About a week," the Katki replied, looking a little bit more comfortable now that any distress caused by his presence seemed to be dissipating.

Peter looked up to me for confirmation while handing the envelope back, and I nodded my agreement.

"A week?" exclaimed Seren, looking back at me incredulously. "And you're ... OK?"

"I told you," I reiterated passionately as I turned back to her. "He's not what I expected."

"Then why do they get drugged?" she probed curiously.

I knew she was partly thinking about Amanda when she asked the question.

"Honestly, I don't know," I replied. "But I intend to find out," I added determinedly.

"Matty," Peter turned on the balls of his feet to address me. "What you've done – what you're doing – it's a huge risk. Even if the Katki aren't what we think they are, you know what the Andekas will do to you if they find out."

It wasn't a question. I knew the risk. The Ravim wasn't just reserved for the Katki. Everyone knew it was an effective deterrent against criminal behaviour. The risk of slavery was disincentive enough for most people to abide by the rules.

"Which is why you can't tell anyone about this," I begged them both. "Please."

"We won't," Peter instantly assured me. "How long have we known you? We know you'll be trying to find answers, and we have every reason to support you." Turning back to continue stroking Tiger, he added, "I just hope you know what you're doing."

While Peter's oath on behalf of them both put me a little more at ease, I hoped his faith wasn't misplaced, and I inhaled deeply before responding.

"So do I."