"Issei is walking down the street. It's been about 2 hours since the events at the occult research club.
A/N- Reminder: Unless explicitly stated otherwise, Issei and Umbris converse telepathically.
Issei: "Well, that was something. I felt like a rabbit in a wolf's den."
Umbris: "Makes sense. You were surrounded by devils in their own base. Your instincts have gotten sharper since you awakened."
Issei: "That's for sure. Anyways, we've got all day ahead of us. Wanna go see a movie?"
Umbris: "A horror one?"
Issei: "What other kind of movie would I go see?"
Umbris: "True, but yes, sounds like a plan to me. I could go for a snack."
Issei: "Alright then, let's get going."
Issei and Umbris went and saw some random horror movie, then decided to go train. As they arrived at their hideout, they both felt as if something was off, chalking it up to paranoia. They got to training.
Issei: Summoning ruin crabs to increase his limit "Fuck yeah, I finally got 4 at once."
Umbris aloud: "Good job, but don't get too cocky now. Ruin crabs require very little mana to summon and maintain compared to some of the things you'll get later. They are children's toys and are useless in combat. We really should get you training with a weapon of some kind."
As Umbris finished his statement, Issei felt a spike of mana instinctually. He jumped to the side. Not a second later, a blast of magic hit right where he was standing. Looking up to its source, he saw a woman, or at least the top half of one. Her lower body was monstrous, and strangely, she was topless, and one of her breasts was smoking.
Issei: "Oh, what the fuck?"
As he said this, the woman thing jumped from the rafters, landing in front of Issei.
???- "Perfect. I was getting hungry, and you'll make a great meal, especially since you're unarmed."
Issei internally: Uh, Umbris, what the fuck is she?
Umbris: Most likely a stray devil based on her energy.
Issei: A stray?
Umbris: I'll explain later. All that matters now is that we can kill her without repercussion from the devil's faction.
Issei: Ok, how do we do that?
Umbris: We have enough energy to manifest my claws. You'll need to close the distance and deal a lethal blow. But be warned, we only have one shot at this. We can't maintain my claws for long.
Stray: "Ah, is the little boy too scared to move? Don't worry, I'm just gonna kill you." And with that, she lunges at Issei. Issei notices in time and dodges to the side. "Looks like you can move after all. No matter, the chase will just make you taste better." She lunges at Issei again. This time, he charges towards her as well, thinking he's defenseless. She's confused but doesn't suspect what happens next. In one swift motion, Issei's right hand transforms into a monstrous limb with razor-sharp claws. With one slash, he cuts straight through her neck, severing her head from her body. Blood begins showering from her neck like a fountain, covering Issei in the deep red liquid.
Issei: "I thought there would be more resistance."
Umbris: "Hmm, what was that?"
Issei: "I thought there would be more resistance, that I'd have to put a lot of effort in, but no, it went right through like a knife in butter." As Issei contemplates this, a black mist begins to emanate from the body. "Wait, what's that?"
Umbris: "Open the book, Issei."
Issei: "What?"
Umbris: "I said open the Tome of Nightmares."
Issei: "Oh, alright." Issei summoned the tome to his hands. As he opened the book, the black fog was sucked into it, and Issei felt a surge run through him like he was just injected with pure energy. "Holy shit, what was that?"
Umbris: "Pure negative energy. I was hoping to get you a little more used to this stuff first, but there's no hiding it now, Issei. In order to get stronger, you need to kill."
Issei: "Huh? I need to kill?"
Umbris: "Indeed. You see, when someone is killed, it releases all the negative energy inside of them, which the Tome of Nightmares can then absorb and filter into you."
Issei: "Filter into me?"
Umbris: "Yes, filter. You see, Issei, you're still human, and absorbing that much raw negative energy would destroy you. But the tome filters it, basically detoxifying it so you can metabolize it while still letting a little pure negative energy through to gradually adjust your body to it. Kind of like taking small doses of poison to build an immunity."
Issei: "Ok, and what does this have to do with me killing to get stronger?"
Umbris: "You see, when you absorb that energy, filtered or not, it's still pure magical energy entering your body. So your natural reserves of mana grow to support the influx of energy, giving you a greater pool of mana in the long run. And the larger the mana pool you have, the more and more powerful of my abilities you'll unlock in the tome."
Issei: "I guess that makes sense, but I mean, I'm not a killer, and I doubt we'll have a steady stream of people I can justify it with self-defense."
Umbris: "I thought you might say that, but I do have good news. We are actually incentivized to kill bad people."
Issei: "Huh?"
Umbris: "The more negative energy the person has, the more of a boost we'll get. So, by killing bad people, we get more energy, and you're technically morally in the right. It's a win-win."
Issei: "I mean, that does make sense, but I mean, do I really have it in me to be a killer?"
Umbris: "Issei, I know you're apprehensive, but it's the only way. Besides, you'll be doing a good thing by killing all those criminals and monsters."
Issei: "Yeah, I guess you're right. I would be doing a good thing."
Umbris: "That's my boy. I knew you would understand. Now, we need to get out of here, like, right now. If she was hiding here, it's because she was being hunted, and it's only a matter of time before House Gremory or House Sitri shows up."
Issei: "Sitri? As in Sona Sitri, the student body president?"
Umbris: "Oh, right. I knew I forgot to tell you that. Yeah, your school's student government is actually just a front for Sona Sitri's peerage. They are all devils."
Issei: Uh, you have to tell me these things sooner, Umbris. You're the one who knows supernatural stuff, guy, gal, uh, thing.
Umbris: You're right. I failed to keep you informed. That's on me. Anyways, let's go.
Issei: Right. I need to take a shower.
Umbris: Good idea.
Issei then made his way home. Luckily, it was late enough that his parents weren't out and about, and his sister and her guests weren't home. He quickly made his way to the bathroom, stripping before he got into the shower. As he stood there in the warm water, he looked down, watching as the red-tinted liquid rushed down the drain.
Issei: Huh. He let out a deep sigh.
Umbris: What's troubling you, my boy?
Issei: It's weird. If you had told me two months ago that the supernatural is real and that I'd be a killer, I would've called you crazy. But now, it's like I'm not even fazed by it.
Umbris: Is this a bad thing? I'd think being able to adapt to this kind of situation so quickly would be a good thing.
Issei: It's not that it's bad, it's just weird, you know? I always knew I wasn't normal, but to think I have some ancient primordial fear god inside me, it's kinda just crazy.
Umbris: Avatar.
Issei: Huh?
Umbris: I'm an avatar, not a god. There's a big difference.
Issei: Oh, whatever.
Issei finished showering but quickly realized he forgot to grab a clean set of clothes. He wrapped a towel around his waist as he exited the bathroom, holding the bloody clothes in his hand. Unfortunately for him, his sister Rias and the blonde girl he couldn't remember the name of came up the stairs right as he stepped out of the bathroom.
Cut to the orc at the warehouse fifteen minutes ago.
The orc had tracked a stray devil to a warehouse on the edge of town, and they were ready to take her out.
Koneko: Hey, Rias, I smell blood, and a lot of it.
Rias: Probably her victims. Who knows how many this one's killed.
Kiba: The president is right. Let's get in there and take her down.
Ichika: Fuck yeah.
But as they entered the warehouse, they were met with an unexpected sight: the decapitated stray sat dead in a pool of her own blood.
Kiba: What happened here?
Rias: Looks like someone or something got here first.
Ichika: Well then, job's over, I guess. We can go home.
Koneko: The white-haired girl looks around. "Hey, Rias, this place is saturated with the same energy that her brother was filled with," she said as she pointed at Ichika.
Ichika: What, you think my loser brother could do this? He's harmless, as weak as a fly.
Rias: We can't rule him out just yet. For all we know, he could have a sacred gear or maybe he's some kind of unaligned monster like a lycan or an undead.
Ichika: I doubt it, but whatever you say, Pres. Either way, the chick's dead, let's go home.
Rias: Ichika's right. Let's all head home. We can report this in the morning. Rest up, everyone.
And so they all went their separate ways, the three girls in the Hyoudou residence getting home just in time to see Issei leaving the bathroom holding his blood-soaked clothes.
Issei: Well, this is awkward.
The four of them stood there awkwardly, not knowing what to do until Rias noticed something.
Rias: Issei, why are your clothes covered in blood?
Issei: Uh, this isn't blood, it's umm... tomato juice. Yeah, I was at a restaurant, and a waiter spilled a glass of it on me. I hopped right in the shower when I got home and forgot to grab a clean outfit, which is why I'm currently standing here in only a towel. Anyways, I'm gonna go get changed. As he turned to walk away, the girls noticed an intricate tattoo on his back that resembled a magic circle with a clawed hand at the center. But you quickly ran to your room, slamming the door shut behind you.
Rias: Ichika, since when did your brother have tattoos?
Ichika: I dunno.
I think we will have to get a closer look at it sometime. Oh, I know, I'll leave an "anonymous" tip at the student body. They'll have to investigate and maybe get us a sketch.
Asia: Isn't that an invasion of privacy, ma'am?
Ichika: Who cares? Either it's just a tat, which clearly ain't yakuza, and it's fine, or it's something supernatural.
Rias: Exactly. Now, I'm exhausted. Let's go to bed.
Ichika: Sounds good.
In your room, as you enter, you catch a glimpse of your back and the sprawling design that now lays on it.
Issei: Oh, what the fuck is that?
Umbris: My sigil? It shouldn't have manifested yet. You're nowhere near powerful enough to be marked yet.
Issei: Explain now.
Umbris: When hosts to powerful supernatural beings grow strong enough, they are marked with a sigil to represent the entity they are linked with.
Issei: So I got mine prematurely.
Umbris: I guess so.
Issei: Oh shit, those three saw it when I turned to run to my room. Shit.
Umbris: It should be fine. Sigils are unique, so it's possible they mistook it for a common tattoo.
Issei: Hopefully.
Umbris: Anyway, Issei, I want to discuss getting you a weapon. I think I have the perfect idea.
Me: And that's a wrap. Sorry it took so long; I had a very chaotic schedule for a while there, so I just didn't have the energy to write this one. But now I'm back. Things are really going to start ramping up soon, so stay tuned. also a cookie for anyone who can guess what type of weapon iseis gonna wield Potatomancer out.