I felt my heart sink at the name. Fred and George stared between Sirius and I as he stood by the door. They probably had no idea what R.A.B was.

But I was just as curious as them, wondering what Sirius could possibly have to tell me about my father. And why was it so urgent?

"Er... all right." I nodded hesitantly. "Why don't you come in?"

Fred stepped aside and we all lowered our wands as Sirius walked inside and into the living room, looking around uncomfortably.

He cleared his throat, saying to the twins, "I was actually hoping to talk to Lexi in private."

"What's the point?" Fred grinned. "She's gonna tell me everything the moment you leave."

I shot him a glare. Thankfully, he got the hint and so rolled his eyes.

"Oh, all right." He sighed. "C'mon, Georgie. Let's go down."

Sirius waited until the twins had left the flat and went downstairs into the shop. The second they closed the door behind them, Sirius took out his wand and casted a few enchantments around the place so no one could hear us.

"Okay, what is it?" I asked impatiently as Sirius put his wand back in his coat's inner pocket again.

"Why don't you sit down?" he said, gesturing at the couch and so we both took our seats, right in front of the fireplace.

"Is something wrong?" I asked apprehensively.

"I went to Grimmauld Place this morning," said Sirius and I gulped.

Harry, Ron, and Hermione were supposed to go there last night, and this morning they had probably seen the sign on Regulus's room, finding out who R.A.B was.

I knew that Kreacher was supposed to take Harry's orders and tell him all about Regulus. But now that Sirius was alive, that meant that Harry wasn't Kreacher's master and therefore couldn't order him around.

So not knowing what to expect, I remained silent and let Sirius carry on and speak.

"They told me about what Dumbledore had asked them to do and all about the Horcruxes."

"Sirius, you can't go with them—"

"I know that," Sirius broke me of quickly, sounding bitter. "Dumbledore had a talk with me a few months before he died... he said that seeing as I wasn't supposed to survive, I mustn't meddle."

I was slightly relieved, but knowing Sirius, I still expected him to act recklessly at some point, which worried me.

"Anyway," he went on, "I visited them this morning; I guessed that they would be there, and I was right. And then they told me about Tom Riddle's cave and the fake Horcrux and the letter hidden inside it, signed R.A.B. I guess you already know who that is, am I right?"

"Regulus Arcturus Black." I nodded slowly, dropping my gaze down.

"Well, I called upon Kreacher," said Sirius. "I ordered him to tell me exactly what my brother had done and — and —"

This time it was Sirius's turn to look away. I saw a flash of hurt pass through his eyes as he struggled to speak.

"And Kreacher told us exactly what had happened... about how Regulus had asked Kreacher to take him to the cave, how Regulus drank the potion, and how he was dragged down into the water by the Inferi..."

"You didn't tell Harry and the others that Regulus was alive, did you?" I asked worriedly.

"No." Sirius shook his head. "But that's not the point, Lexi... How did Regulus survive? He was dragged under the water by the Inferi! That's impossible!"

"I know that," I said in a small voice.

"But there was something I noticed."

My head shot up at that curiously. "Wh-what?"

"It's about Kreacher... I kept asking him how Regulus had died and he just kept repeating the same sentences over and over again. He wasn't even changing a single word."

"What sentences?"

"This," said Sirius, and so he started repeating Kreacher's words, "Master Regulus told Kreacher to take it and, when the basin was empty, to switch the lockets. And he ordered Kreacher to leave without him. And he told Kreacher to go home and never to tell my Mistress what he had done but to destroy the first locket. And he drank all the potion and Kreacher swapped the lockets and watched as Master Regulus was dragged beneath the water."

I felt chills running down my spine as Sirius repeated Kreacher's words. It was still hard for me to believe who my father was, after knowing him as a Muggle man my entire life.

"See how I've managed to memorize what kreacher told me?" said Sirius. "It's because I asked Kreacher to tell me the story ten times. Harry stopped me at last. But he didn't notice that Kreacher wasn't changing a single word of it, no matter how I asked the questions."

"Er... so?"

"So something doesn't add up!" Sirius explained. "Regulus must've told him to tell the story just like that, just in case someone asked; although he had asked Kreacher not to tell our mother anything."

There was a moment of pause, and then it finally hit me. "So you think Regulus had asked Kreacher to lie about what happened all along?"

"Exactly." Sirius nodded firmly. "Regulus must've gotten the locket somehow and managed to escape and Dissaparate from the cave with Kreacher."

"But I still don't understand," I said. "Why would Regulus want to lie about his death?"

"Maybe because he wanted everyone to believe that he was dead," Sirius suggested. "He was probably scared that the Death Eaters would track him down."

"Yeah, but why?" I huffed in frustration. "Why would Regulus leave the locket for Kreacher to destroy? Why would he go through all this trouble, to put himself through all that pain, only to leave the locket behind and run away to start a new life with a new name as a Muggle man?"

Sirius looked just as confused as I was, having nothing to answer me as he stared into distant, thinking.

"It's not just that," I went on. "Something else happened that day. I can feel it. Something made him change his mind."

Sirius shook his head. "How can you possibly know that?"

"Because I know my father. Because I know he wouldn't have given up on such thing for no reason, or merely out of cowardice. Something must've happened... I just don't know what."

I then sighed in exhaustion, burying my face in my hands as my head started hurting with all the possibilities.

"I'm tired of mysteries, Sirius," I whispered, dropping my hands and staring into the empty fireplace. "That's how my whole life has been... a mystery. I was lied to my entire life about who I was. Or about what family I come from. And I'm just tired..."

"Lexi —" Sirius sounded like he was going to try and comfort me, but I broke him off.

"I have to know what happened that day that made my father run away from the magical world like that, leaving everything behind and making everyone believe that he was dead, with his body never being found —"

But in mid-sentence, I came to a sudden halt as I suddenly remembered something.

On the day I had told Dumbledore that Regulus Black was alive and that I was his daughter, many curious things happened.

The moment I told this to Dumbledore, he started pacing around, obviously thinking hard, until he had finally said mostly to himself,

'No wonder their bodies were never found...'

I took aback at the time, having to idea what he meant by 'their'. But he then made me even more surprised when out of nowhere he suddenly asked me whether 'Lexi' was my full name, or if it was short for something else.

To the answer, I told him that my father wanted to name me 'Alexandra', but my mother said that it was a little old-fashioned and so they decided to call me 'Lexi'.

Once I had told this to Dumbledore, I saw a curious flicker in his eyes, as if he had understood something at the time that I didn't.

Was Dumbledore keeping more secrets? What was so important about my name and Regulus's disappearance? There must've been a connection, otherwise Dumbledore wouldn't have asked.

"Lexi?" Sirius called me again, dragging me back to reality. "Are you okay?"

I blinked a few times in realization, my heart pounding in my chest as my head started hurting even more.

"What if Regulus wasn't alone that night?" I muttered mostly to myself, before I looked back at Sirius and said, "Do you know anyone named 'Alexandra'?"