You're starting to worry about when the robot will return to cause more trouble. They know that you're onto them now, and are biding their time and waiting to strike when you least expect it. It would be an incredible disaster if they were allowed to inject their chemical weapons into farmland or water sources. Barbara and Mitsuru have been working diligently to poison-proof as many locations as possible with surveillance and assessment from the AI system.
That has freed Mitsuru up to work on her other door project – one which will allow a more natural transfer of chosen individuals between your worlds. With that said, the Sledgehammer will still be needed to summon them to your location. Making them walk all the way from the garage every time an attack happens is not a feasible plan.
But before any of that can happen, you're intercepted by a familiar face as you walk around the city to try and finish off some of Mitsuru's chores. It's your 'son' from the future, Zandias. You aren't sure why the crimson-haired scamp sought you out when nothing is going on, but you decide to hear him out and gain some insight as to what he's here for.
"Can I help you?"
He smirks, "So cold to your own kin. I guess it makes sense when you haven't raised me just yet…"
You follow him away from the bustling streets and into a quiet park close by. He sits down on one of the benches and invites you to join him. There's a moment of serenity as he observes the green grass and birds fluttering between the trees. He's thinking of what he wants to say.
"You know, you and Mom told me that it didn't really matter what I said or did back here. Everything that I do has already happened, as it has happened hundreds of times before. Part of me wanted to spend time with you all and see how things were before I was born."
"You haven't been around much though."
"True. Maybe I'm just a little scared of seeing a younger version of you? I've always looked up to you and Mom, and all of my other Moms. You're always doing what you think is right. You're brave. Braver than me." Zandias swings his and chuckles, "Seeing these 'humble beginnings' of yours makes me appreciate it so much more. Even before you became the strongest man in the universe – you were still risking your life to do the right thing, working out of this old garage with Mitsuru…"
"Things will change."
"They will. In a million little ways, they'll change. You'll have me, and other kids, and you'll learn to protect the peace of the multiverse using so many amazing powers. You'll help the Gremory clan rise to the top of the underworld, and even more besides that. To think that I only came here to give you that scientific paper and set up a few dominoes for you."
"That's it?"
Zandias rolls down his sleeve and checks a digital watch, "Correct. I'm afraid that my part in this story is done soon. It takes a lot of magical energy to keep me here, and I need to be getting back home to the present now that my job's done. I hope you won't miss me too bad."
"We've barely interacted," you observe.
"That's for the best. Mom said I was a little hellraiser when I was younger – you'll be sick of me soon enough."
You laugh, "You're not filling me with much hope here."
"Consider this my pep-talk. Everything that has happened will happen. I can only promise you that the future is bright, all you have to do is keep going. Never lose that faith that doing the right thing will reward you."
You smirk, "Isn't it weird giving advice to your own father?"
He nods, "You're damn right it is. But that future is yours if you're willing to aim for it. You're the hero, and the Incandescent Devil Emperor. A lot of people have you to thank for preserving peace across the multiverse. Just don't forget about little old me when you're rich, powerful and successful."
"There's no way I could ever forget meeting my own adult son."
"I think this is the last time we speak, before I'm born, anyway. So I think I'll just leave you with that. You already know what to do, and what's at stake. When I get back, I'm gonna' tell you just how much I appreciate what you did."
"Trying to make the old me cry?"
"Partly, but you've gotten pretty good at resisting the sappy stuff. Hell, the last kid you had didn't even phase you. That's what happens when you start having so many of them. Do you know how many people call me big brother? It drives me crazy."
"Nothing wrong with a big family, it sounds to me like you're too reliable. Now they're all counting on you."
He sighed, "That's the exact same thing you said to me when I mentioned this the last time. I guess people really don't change that much – even decades into the future. Anyway, I need to get going before they completely run out of mana. Wouldn't want to be responsible for anyone in the family hurting themselves just to amuse me."
He stands from the bench and offers his left hand for a firm shake. He's treating this more like a job interview than meeting his Dad in the past, but you wouldn't know how to end things either. He doesn't have to worry about you having second thoughts because of how he behaves, he sounds like a good older brother, and a worthy heir to the house that you seem destined to build together with Rias and the others.
"Seriously, you have no idea how crazy things are going to get."
"Oh, I do. We're already creeping up the chain to some of the superheroes…"
"Like I said, no idea. I know you're an amazing guy, but how you manage to handle some of my aunts is beyond my comprehension."
"I guess we'll see."
Still hesitant, but knowing that his time in the past is up – he gives you one last salute with his fingers and summons a magic circle beneath his feet. "Catch you in the future, Dad."
"See you then."
He slips away through time and space, leaving you alone with your thoughts once more. It was an uneventful ending to his time in the past, but that was all it was ever meant to be. A small nudge in the right direction for Mitsuru from her future self, a stack of dominoes that would soon fall and allow you to save the world. His words still ring loud in your ears. All this talk of destiny and time travel is tiring to say the least. You're left with a lot of questions – but he was never going to answer any of them in great detail. The only thing you can hope for is that he is who he says he is, and wasn't just part of some hare-brained scheme by the aliens to get one over on you.
"I at least expected him to save me more than once…"
But once was enough, you suppose. If not for him – you would have never survived your initial fight with Vali and the imposter. He was the one who led you down the path of unlocking your Mantle form. That's all he needed to do. A self-fulfilling time loop that would lead to his own birth.
But damn, you're going to marry Rias and have kids? She was very plain speaking when it came to her desires, but it still shocks you to imagine it. You grab your bags and groan, you still have more chores to complete. Hopefully it'll take your mind off of the future. It's kind of worrying to think about.
When you return to the garage sometime later, there's a surprise guest tinkering at Mitsuru's workbench while the woman herself is mysteriously absent. It's Android 21. She's so engrossed in messing with the gadgets on the bench that she doesn't notice you until you place the bags down on the table.
"Oh, you're here?" she smiles.
"Hello Twenty-one. What are you working on there?"
She holds up one of the devices, "Mitsuru asked me to help her improve the communications module she placed into all of your phones. They're a terrible drain on battery life."
You didn't get a good chance to speak with 21 the last time she was here, Bulma whisked you away to the showers for some fun, and 21 was too busy helping Mitsuru work out the kinks in her systems to worry about you. By the time everything was resolved, it was late and they needed to head back. 21 is the most radically different version of a character you've summoned thus far – in that she is both alive and living happily with her other personality.
It helps that Mitsuru searched for a universe where her evil side isn't quite as evil. There'll be no eating living beings for her – just a glutenous streak and love of sweets.
21 has an inquisitive look on her face, "Mitsuru has already informed me of the impressive harem that you've put together. I don't suppose that you'd have an issue with me joining in?"
"I didn't expect you to be so forward. I'd be honoured to have you."
21 smiles and adjusts her glasses, "My analysis of the data is without fault. An assessment of your tastes and previous incidents has made it clear that the direct approach is the most superior. I can feel my more impulsive side getting excited just looking at you. That is a good indication that you will make the perfect partner."
"I see. Welcome to the family. I'll have to introduce you to everyone else eventually."
"I have already given my regards to your other partners through the messaging network, but an in-person meeting is more conducive to good relationships…"
You walk around the table and take a closer look at her work; "There's no rush. I can only summon so many people at once in the first place, at least until Mitsuru completes her doorway project."
"Ah. I understand. Don't be afraid to call on me should you require my assistance. Even when my hunger is sated, I am more than capable of defending myself and defeating your foes." She punctuates her offer by reaching down into a bag of gummies and swallowing several of them at once. Now that you notice it – there are several other empty sweet packets littered around the place. She's been eating a lot since her arrival here.
The door to the back hallway opens and Mitsuru emerges, "Oh. I didn't realise you were back!"
"Yeah – I got everything you asked for."
Mitsuru wanders over to the shopping bags and checks through the haul. Money is no object to you or her now, but that sometimes brings up another problem. Certain materials and machine tools are incredibly hard to get. Money can grease the wheels, but not if there's a shortage of certain parts or rules in place that keep you from getting them.
Mitsuru has run head-first into those issues several times now, which inevitably add delays onto her projects she'd rather not deal with. Several suggestions have come and gone, but transporting materials permanently through the universes is a difficult problem to solve.
Just like how the characters you summon have their own gravity that pulls them back, so too do the items that they bring with them. This can have strange and unintended consequences should you utilise those materials in construction. Mitsuru ran a material test using a bag of concrete taken from the Major's home dimension.
She mixed it, laid it into a block, and let it dry before sending her back. Suddenly the composite elements that were holding it together disappeared with her, leaving nothing but a puddle of water; the same water that was used to mix it.
There is one theory that Mitsuru has. The invaders must be using a large-scale anchor system to keep themselves tied in place. The amount of energy that must be demanded defies rational belief. It was the only concept that made sense to her.
You also floated summoning Momo from My Hero Academia to make elements and materials for you – but Mitsuru shot you down. She'd need an extremely detailed breakdown of them before making them, and Mitsuru wasn't certain if those materials would travel back with her as well.
So at most, you can gather things from this world for the time being. Mitsuru has never been all that concerned with matters of the law. She believes earnestly that everything she does is for the greater good. You're not liable to disagree with that perspective having known her for a decade plus. Despite her intent to break the rules and get what she wants, Mitsuru doesn't know where to start or how to execute her schemes.
"We seriously need a bad bitch."
You double-take, "A what?"
"A bad bitch! Someone who doesn't care about breaking the rules. Someone who'll get what we want without any messy questions about ethics or morality!"
"I've never heard you swear like this before."
"I'm manifesting the type of rebellious spirit that we're looking for! Give it some thought, please."
When Mitsuru says bad bitch, the first character you think of is Rebecca from Black Lagoon, and she's a smuggler too. But you don't know how easy it would be for her to apply those skills to an unfamiliar place with unfamiliar people. She'd need time to build a network, work out how to get the stuff to and from the garage without suspicion, and that's assuming she even agrees to do it for you.
"Yeah, I'll think about it."
You kick back on the couch and rest your legs while 21 and Mitsuru work. They get along very well, having similar personalities and interests. You feel like a bit of a third wheel hanging back and spying on them the whole time. There's not much else for you to do without some bad guys to batter, so you consider summoning one of the girls for a quick date or chat. You haven't spent time with Motoko in a while, and she's marked as available…
Why not? You send her a message and arrange a meeting.