The next morning, I awoke to the shimmering light. In the complete darkness of the cavern, it was like a shining beacon. It sparked, and then went out, only to spark once again. Glancing over to my right, I could see Olivia kneeling there, facing away from me. Her hands together and a ball of fire erupting between them. She was wearing her clothing, which appeared to be dry. She was focusing on a spell that appeared to be difficult for her but seeing as the hallways felt warmer than before, the initial worries of hypothermia were solved.
“Achoo!” I ended up letting out a sneeze.
Olivia froze from casting for a second but then continued after speaking. “We can go once you’re ready.”
I glanced down, realizing I was still naked. However, my clothing was dry and neatly folded at my feet. Moving to my feet, I quickly put the clothing on. It was wrinkly, the effect of being wet and hastily dried, but it was still a load better than walking around in damp clothing. I suspected Olivia must have done something to fix this. A single night shouldn’t have been enough to leave the clothing this dry.
Once I was finished dressing, using the flickering light between them intermittently appeared between Olivia’s palms as my guide, I finally looked over her shoulder. I could hear her mumbling an incantation under her breath.
“What are you trying to do?” I asked.
She finally stopped her casting and shot me a sidelong look, “I’m trying to create a warmth spell without creating a fire. I managed to dry our clothing and set a fire for a short while, but I don’t know if we have any access to the… never mind, it’s complicated, you wouldn’t understand.”
I nodded, glancing around. “We’re underground. Fire will burn oxygen and create carbon dioxide. Without a proper air outlet, we could obtain warmth only to asphyxiate.”
“Carbon wha-? Ass fix…” She blushed, and then suddenly punched me. “Nya! Are you trying to tease me!”
I stumbled back with a grunt, “No, damn, that hurt… I mean we could suffocate down here if we use to much fire, right?”
She was shooting me a suspicious glare, but then with a flick, she created a light source and stood up. “I suppose you at least understand that much.”
I could only roll my eyes in response. I had already discovered while training under Baba that my understanding of the sciences from my old world had allowed me to quickly grasp how to manipulate things magically. Even my base levels of understanding light, refraction, and wavelength allowed me to grasp illusion to the point it impressed Baba. A normal person would have taken five years to get the point I had reached in a mere month.
I wondered if I gave Olivia some lessons on thermodynamics if she’d be able to get the heat going. I decided that wasn’t important in the end. We didn’t plan to stay here long enough that we were going to need that option. With luck, we could meet back up with the goblins today.
As I got up and the pair of us started heading away from the waterfall and into the depths of the cave system while guided by Olivia’s light, I realized my leg was incredibly stiff. At first, I figured I had slept on it wrong, but rather than working out the kinks, the problem continued to get worse. After about thirty minutes of heading down the corridor, I was limping now, and a sharp pain was in my leg.
Olivia, who was taking the lead with her light source, hadn’t noticed that my expression was turning pale. So, it came as a complete surprise to her when a sudden thump sounded behind her. She spun around to see me laid out on the floor.
“Nya? What is wrong?” She demanded, her eyes flickering worriedly.
“Ah… I think I was bitten by one of the spiders?”
“Spiders? You were poisoned!” A flash of worry appeared on her face. “Why didn’t you say anything earlier!”
I turned around and moved myself to lean against the cave wall. Both legs felt numb now.
“I didn’t think there was a problem. Devilkin are resistant toward poison.”
“Resistant isn’t immune!” She growled, coming over and sitting down on her knees next to me. “You shouldn’t have kept this a secret!”
The previous night, we hadn’t had time to worry about it, and I figured that if the bite truly had venom in it, it would have already affected me by now. The cold temperature, my lack of moving, and my devilkin blood must have kept the poison from spreading. It was only once I started walking that the poison started truly spreading. The numbness was now spreading through me rapidly.
“You fool. Those spiders must have a dreadful venom.”
“Actually, I’m probably lucky they were spiders though.”
“Why do you say that?”
“Spiders want their victims alive. This is probably a paralytic. It shouldn’t pose me any danger, but I may fall into a state of a coma if it spreads much more.”
“Nya! How can you be so calm?” She cried out.
“I-isn’t… big sister here? You… can help…”
The poison seemed to be spreading fast now that it initiated. In just a few minutes, I was already having trouble talking. I had been really lucky that I hadn’t slipped into a coma during the night when Olivia was passed out.
Olivia blushed. “N-now you’re depending on me…”
“Y-you can’t help?”
“I-I can do it… I was taught how… by the elves. It doesn’t even involve magic, but it’s a special technique.”
“Th-that…” her face grew slightly red. “I just… need to know… where the wound is…”
She seemed to grow shyer by the second, but I couldn’t hear that last part. “What?”
“The wound! I can suck out the venom through the wound. It’s a special elfish counterflow technique. It reverses the flow of poison. Nya… just show me where it bit, okay?”
“Ah… that…” I reached down and grabbed my pants.
“Wh-wh-what are you doing?” She cried out, pointing at my pants, which were now lowered, exposing my undergarments.
“The wound, it’s on my… right…” I hadn’t been thinking clearly.
The spider bit me on my inner thigh. That meant that Olivia would need to suck… down there. Both of our eyes traveled down to the wound sitting only about two inches away from that. Even though there was a cloth covering it, it was still very close for a brother and sister to get.
“Nnnnnnyaa… damn it!” She cried out. “I won’t do it! Brother should just die!”
“O—kay…” My eyes rolled up in my head and I collapsed.
“Ah! Brother!” She cried out, grabbing onto my shoulders.
However, when I didn’t respond, there was a moment of silence, and then I felt my leg being grabbed. Of course, I hadn’t actually passed out, but this was the inevitable conclusion anyway. Olivia had to use the technique. I was just edging her along a little bit quicker. The sooner the poison was out of me, the better I could recover. I couldn’t have her being squeamish until I really did pass out, so I decided to throw in a bit of encouragement.
Feeling her hands on my thighs, it was a bit more stimulating than I expected. With my eyes closed, I could only imagine what she was doing, and with the feel of her hot breath on my thigh, my mind naturally went back to last night. I recalled the feel of her naked body pressed against mine in the dark.
A moment later, I felt her lips on my leg. She bit it first, opening the wound, and then she began to suck out the poison. The feel of her warm lips and the sucking sensation on my thigh hurt for a moment, but then it started to feel good. As she kept going, her gentle lips working rhythmically, it went from feeling good to feeling more than good. The thoughts of her naked shot back, and I had to bite my lip to keep from making a noise. Furthermore, my hands squeezed my own hips to keep me from grabbing her head.
She continued to suck, and then spit, suck, and then spit. As she readjusted herself, he hand moved up my thigh and then struck something hard with her wrist.
“Nya? What’s this?”
Her fingers suddenly grabbed it through my underwear. My eyes immediately popped open and I shot up into sitting position, shooting a look down at Olivia with shock on my face.
Olivia was between my legs. She had one hand on my thigh and another wrapped around my cock. She was looking up at my cock with wet, puffy lips. It was an exceptionally lewd scene.
“Nyaaaaaaa!” Olivia leaped up and attacked me.
“Help! Ah! You’re going to kill me!”
“You devil! Monster! Pervert!”
It took nearly fifteen minutes until she was finally settled down. Fortunately, her technique had done the job. I could move my legs again, and the numbness was rapidly disappearing. I stretched my legs a few times with an impressed look on my face. However, when I glanced in Olivia’s direction, she had her arms across her chest, red in her cheeks, and a glower on her face.
The two of us started moving again, but this time, there was an awkward atmosphere between us. It seemed like for every step forward I moved with her, I ended up losing a step. In short, I was going nowhere quickly. I started pondering how I was going to break that final shell between Olivia and me and finally gain her trust. In the end, would I really have to enslave her to ensure her loyalty? I had these kinds of concerns.
Even though Olivia had the light, at some point, she fell behind and started following me with her head lowered. Perhaps, she thought I knew the way. In truth, my guesses were mostly random. I tried to use airflow to decide, as well as elevation. We had made a dozen turns, and I think we were getting closer to the surface. At the very least, we weren’t reaching a dead-end. As long as there were more paths to explore, there was a chance we’d get out of this place.
At that moment, I felt Olivia grab the back of my shirt. I glanced back, surprised by the gesture, but she had her head down and her expression gave nothing away. Perhaps, she just wanted to make sure that she didn’t lose sight of me or I didn’t move farther ahead. She didn’t say anything though, so I just turned back and continued to move.
After traveling for about a day, I could hear Olivia panting behind me. We had done a lot of walking today, and it was anyone’s guess if we were any closer to the surface. It apparently reached Olivia’s limit, so I decided to stop here for the night. We hadn’t said more than a word or two since this morning if one could say it had even been a whole day. Under the ground, it was impossible to tell how much time had passed.
“We’ll stop here,” I said to the quiet Olivia, prompting her to let go of my shirt.
“Yes.” She said simply.
I sat down, pressing my back against the cave wall, instantly feeling the chill of the cave and making a face. While moving, it was easy to stay warm, but now that we were stopping for another night, we’d need to resolve things. I’m sure that Olivia would not appreciate spending another night naked with me.
“Come here for a moment.” I looked up at Olivia and blinked.
She was looking at me, but she was also distant, hiding in the shadows. I could also hear her taking deep breaths. Was she really that tired? I couldn’t let her sleep just yet.
“Come over here.” I beckoned, bringing out my hand.
Olivia looked at my hand for long enough it felt awkward, but then she reached out and grabbed it. I pulled her forward out of the light. She still had her head down, and it was difficult to see her face. After a day of casting light, it had dimmed considerably, being little more than candlelight. Perhaps that was why she was so tired right now.
“The spell from this morning, the flameless heat. I’m sure it can be achieved. We should try to cast it before we go to sleep tonight.” I explained.
“I-is brother cold?” She suddenly asked, her voice sounding somewhat strange.
“I will be tonight.” I continued. “We’ll need to generate some heat so we can sleep a bit more comfortably. Okay?”
She looked at me for another long moment, her eyes shrouded in darkness. At this point, I started to realize that something was wrong with her. She was still breathing hard. Her tail was flicking back and forth chaotically. Her entire body appeared like a cat ready to pounce on a mouse.
“Olivia? Is something wrong?”
“I-I can’t…” She tried to pull away, but I still had her hand, so I tightened my grip. “Please…”
She only pulled once, but then she shot me a look. I finally could see that her eyes were red, and her face was flushed. It looked like she was suffering from some kind of illness.
“Olivia, are you okay?” I demanded in surprise.
It was only when I saw her eyes flicker with a lewd desire that it suddenly dawned on me. She had sucked the poison out of my leg. At the time, I hadn’t even been thinking about it. The poison must have been dulling my mind. She clearly ended up with a lot more than just poison in her mouth. More specifically, she had ingested some of my blood!
“I will… make brother warm…” She said this as tears fell from her face.
“Ah!” I let out a cry as she pulled off her clothing.
They fell noiselessly to the ground, and suddenly I was looking at my sister, completely devoid of clothing. She had a rather normal-sized chest, although still bigger than the elf sisters. She had shapely hips, a long tail, and a beautiful body.
Before I could move at all, she pounced, wrapping her legs and then sitting down on my lap. “Brother, be gentle…”
“Hah… that…” Her lips took mine, and the pair of us began to kiss.
She tasted sweet, and her body was warm. After sleeping together the night before, I couldn’t say I wasn’t tempted. She was Prince David’s sister, but I was just a man from another world. Even so, a part of me saw her as a sister anyway.
Isn’t this what you wanted? Isn’t this what you were aiming for? Even God wants this!
My mind didn’t help either. Rather, if I could have my sister now, then that would resolve a lot of problems. I would finally have one sister under my control, and I could use her to help entrap other sisters. From a purely tactical point of view, forcing her into submission seemed like the best course of action.
Olivia’s hands fell to my pants, and she started to eagerly unzip them. As soon as she pulled out my dick, I gasped as her delicate hands started to stroke it with vigor.
“I’ll make brother warm, okay?” She said, looking up at me tearfully. “I’ll make Brother feel good.”
“Olivia… we can’t…”
“Then… brother can… c-cum in me…” She blushed, “I want Brother to cum in me.”
“Hah hah…” her hands felt good, and her body was pressed against mine.
However, a small part of me still seemed to want to resist. At the end of it all, she was still my sister. How could I force her into this? I just couldn’t. I gritted my teeth and then reached down and grabbed my dick, pulling her hands off and then rubbing it hard.
“Ah! B-brother!” She looked down at my dick wide-eyed while I stroked it aggressively.
“I love you, Olivia…” I said, kissing her.
Our lips kissed lewdly, and my hand stroked my cock. Naturally, under these circumstances, I came quickly. Feeling a relief as I came, allowing me to think more clearly, I finally pulled my lips away. Olivia was panting again, and saliva connected our mouths. She went to kiss me again, but I brought up two fingers covered in cum and stuck them into her mouth.
“Mm!” She made a cute noise, a look of confusion on her face.
But then, she started licking my fingers, her sweet pink tongue dancing across as she ingested the cum. In the end, I had resisted. I didn’t even know if Olivia would ever forgive me after this. I might have lost all progress with her. However, my aphrodisiac could be expunged with any ingestion of devil cum. It didn’t need to be in her vagina, where she’d become pregnant and enslaved. Since her arousal was broken, I could finally relax and deal with the outcome of this mistake.
Olivia finished licking my fingers and then gave me a weird look. “Is this… some kind of weird devil thing, Brother?’
I could only chuckle and shake my head. “No… but… that will cure the aphrodisiac from you tasting my blood. We don’t have to have sex now.”
Her eyes narrowed, her expression starting to change as the cum took effect. “Nya? You don’t want to be with me?”
I sighed. “I want you. Damn it, I do… but not under some influence…”
An angry expression started to form on her face as the arousal left it, suddenly she hit me on the head. “Then why did you finish yourself off, you dummy!”
“What?” I grabbed my head while looking up at her in confusion.
“You stupid brother! Don’t you think I thought of that before I did it? My technique doesn’t take up any blood! I’m not on some devil aphrodisiac!”
“Stupid brother! After you passed out… I was so scared, and then you got aroused! I spent all day working up the courage and then you just jack off in front of me! You pervert!”
“You want to have sex?”
“Not now! I hate you! You’re the worst! You’re… Mmm!” My lips found hers, but she managed to escape. “Don’t think you can now! You ruined it! Besides, you’re already spent!”
“I can go again!”
“Then fix it yourself! It was a one time offer! Nya!”
This time, I pushed Olivia to the floor and I didn’t stop.
“Nya! You… Brother… n-no… oh… oh… ahhhh… ahhn…I love you… brother…”