Avenger and Shielder
They were born out of sheer luck. One was an AI of a comatose human, the other a glitch female copy. They were fated to die, but Hakuno Kishinami, after winning the Holy Grail War, decides that he and his other self's journey isn't over yet. In a new world where dice determines your fate, they strike out to live their new lives uncontrolled by observing 'gods'.

AN: Quick note Hakuno's weapons are like the fanart Mashu Alters, one looking like the doujin comic with weird prongs/spikes, and the other looking like the one who created Mordred Alter, Scatach Alter, Marie Alter, and Liz Alter, and his armor is that of Mordred Alter(which fanart version you pick doesn't matter). Hakunon's shield is a larger and whiter version of Mashu's and her armor is a version of Saber Mashu by Untue.

So quick summary so I don't have to awkwardly place it during the story scenes.

GS escapes(as opposed to hiding and witnessing what happens) the village believing it to be completely destroyed, but they show up in time to save a small handful of women including his sister. Despite looking like children they retain their skills, so they quickly make work of the Goblins from afar.

In the five years since that attack GS retains his canon hatred of Goblins due to being taken in by Burglar(who if you don't know, is his teacher and somewhat savior, as well as the reason for his shitty social skills), believing his village was destroyed and his loved ones killed, plus seeing the atrocities Goblins commit in that timeframe.

For the Kishinami Twins, they entered the world and were able to take care of themselves because they had code casts and could create mystic codes. They would eventually go on to help the Sword Maiden and her party defeat a demon lord, but were known by the titles Archer and Assassin as they were not yet capable of fighting beasts head on. They help Sword Maiden with her trauma and as such she's Tamamo/Nero levels of attached to them.

By the start of GS episode/chapter 1 they are both 19 and made GS just the slightest bit more talkative and less reckless as he reminded them of [Nameless] but worse.

Hakuno is Avenger because he keeps the memories of the dead with him and lives/fights for what they couldn't have. Hakunon/Shirono is Shielder because she wants people to live fruitful lives. They don't join GS on quests a lot because despite acknowledging the threat of Goblins they are disgusted with them and prefer to deal with other monsters unless they believe there are women that can still be saved, hence why he's still not as developed as he becomes when Priestess and HEA join him.

They are friendly and help other adventurers through the price of favors, as some are either wary of free help or won't accept it, and use those favors for either quests or embarrassing the adventurers like forced cosplay or eating Mapo Tofu.

Anyways, that's all that needs to be said as anything else can be revealed through the story.

Chapter Start

Guild Girl forced a smile as yet another group of rookies stood in front of her, ready to take a quest they didn't fully understand.

"C'mon, it's just a bunch of Goblins! How hard can it be?" A line that quickly spoke of ignorance.

All experienced adventurers have long since understood the disgusting trickery Goblins laid. They were like feral bandits, but more difficult to their inhuman bodies and environments. Even rookie adventurers, the ones with the guts to ask for advice, knew Goblins were dangerous. To speak of them so lowly simply due to their 'average' strength was the height of foolishness. The reason most Goblin quests weren't taken by adventurers as simply because everyone who's experienced their nastiness didn't want to go through it again unless it was one of the few quests on board or if they wanted to rescue the kidnapped women.

Adventurers 'knew' the risks in taking quests, as such the guild, and Guild Girl, do not take any responsibility should they die. They had no obligations toward preventing their deaths.

But that didn't mean she didn't care if they lived or not.

"Now now, this is your first quest as adventurers. Goblins are weak that you can all individually kill them, but they tricky to deal with especially on their own territory. It's important to know what your dealing with before leaving, and our experienced adventurers are all more than kind enough to give you advice." Technically she wasn't supposed to be giving advice, but as some of her good friends told her, if it wasn't completely against the rules, or wasn't caught by someone with authority, you can do whatever you want and help people however you see fit. Most young adventurers occasionally came to her for advice for small matters like this anyways, such as if they lost a sword or want to know which adventurer knows about which monster. These rookies may not have asked for her advice, but as long as they weren't smart or prideful enough to call her out on it, she wouldn't get in trouble, and might just save their lives.

Warrior was mesmerized by her words, and she knew her gamble saved a group of rookies. "Seriously!? They won't get mad if we talked to them?" She pegged him as one of those kids who grew up admiring heroes and adventurers pretty quickly into their exchange of words.

She forcefully giggled behind her hand. "Of course. We have Frontier's Kindest adventurers in this guild." She looked over to the tables and identified her two brown haired friends. "Those two over there, the lady with a large shield with a cross, and the gentleman with different blood red colored spears, are among our kindest. They have no qualms giving advice to others, and even give different types of assistance for the price of a single favor to the both of them. You can chat with them whenever you wish and they will not get angry."

Fighter and Priestess looked at them in open admiration with Warrior, while Wizard tried to hide hers with her hat.

"Well...perhaps a quick talk wouldn't hurt anyways?" Priestess asked. Guild Girl approved of this one, as she was the most cautious and heeded her warnings from the beginning. It was clear the younger girl was trying to push her party into being safer as she was worried about the quest not going well. Despite, or perhaps because it was going to be her first quest she was very cautious.

They walked over to the older adventurers. The young woman held a shield larger than her body and had sleek white armor that covered black skin tight spandex. The young man wore black armor and just looking at his red spears made them shiver.

"Hm? Oh Nii-san! It looks like Guild Girl has sent another batch of kids to us! What do you think they'll ask? I'll bet it's equipment!"

"I have eyes too Nee-chan. You don't have to call them out. I'll bet it's about a quest involving disgusting creatures."

Said rookies quickly lost their confidence hearing the two were obviously twins speak.

Priestess found her voice first, and was slightly flushed. "Ano, we were suggested to ask you for advice, um, regarding goblins?"

The male gave a small smug nod as his shorter twin sighed sadly.

"U-um. If we're bothering you..." she continued to say.

The two waved her off in sync.

"It's fine. This is just-"

"How we can be."

The Shielder then leaned forward and patted Priestess on the head. "Fufufu. What a cute child. Don't worry, this Onii-chan and Onee-chan will always help you out if you need it."

"Although, before you go nearly get yourselves killed by goblins, you should make sure you have the proper supplies. It's a cave, so long swords are a hindrance, and not having even chainmail or potions is asking to die quickly."

The younger teenagers winced at his harsh words as he saw right through them. However, they didn't accept his words so easily.

"T-they're just goblins! They aren't that tough!" Warrior said.

"Scorpions and snakes aren't so tough either, but all it takes is one hit from them to kill you." He stared Warrior down, unimpressed. "Goblins are weak, but they're relentless. Kill one and two more are right behind the one. Rookies like you can't take on more than two at a time, but trying to fight them all is like trying to fight an animal herd or a flock of birds. There's a reason adventurers avoid goblins kid, and it ain't because they're just weak."

Shielder flicked the boy's forehead. "Exactly! If you don't properly understand what you're fighting, you leave yourself open to getting killed in ways you don't expect. For example, did you know goblins liked to use poison?"

Their heads moving back in surprise gave them away.

"Not only that, but even goblin children who act all afraid will kill you the moment your back is turned, and plenty of adventurers fall for their possum acts."

Fighter gulped. "Surely they aren't so difficult? Goblins are small, and I can't imagine they have the strength to pull any of that off."

The male twin snorted. "Goblins that live long enough have the strength of grown men. And even their smallest show surprising strength sometimes. Don't forget, even a weak blow can be a finisher if it hits somewhere vulnerable. They're unintelligent, but not stupid. Even animals know to go for the neck."

"My magic-" the proud Wizard began to speak but her mouth was covered by Shielder.

"Magic isn't something that can be cast consecutively or quickly you know. If you get ambushed or face more than a few, it'll be the end for you, and death would be a lucky fate of yours." She ominously said so cheerfully.

Priestess by this point was beginning to sweat. She couldn't fully imagine the threat goblins were, but she trusted the Twins' words, and wasn't feeling confident in joining the quest.

The male twin, seeing this, sighed. "But, if you're still willing to go on the quest, there's someone we know experienced with goblins who will make sure you get out of there alive and give you good advice."

Fighter nodded furiously. She clearly didn't comprehend the threat they were facing, but was willing to add another party member. "There are women who were taken by the goblins! We have to go save them!"

"Goblins?" A voice appeared behind them and made the teens jump. He wore dirty armor and had a helmet on.

"Yo Goblin Slayer. These rookies are dead set on taking this Goblin quest. Do you think you can join them and make sure they understand what their dealing with? Shielder and I will take care of your payment, so leave the reward to them."

"I see. I can kill goblins." He said stoically. The twins knew he would go along not only to make sure all the goblins died, but to make sure to limit the casualties as Goblin Slaying was dangerous to leave to the hands of the inexperienced.

"E-eh?" Wizard was confused at the sudden development.

"Don't worry. Goblin Slayer is a silver rank and he taught Avenger and I plenty of fun ways to deal with Goblins. He doesn't look like much, but you better listen to his orders or Nee-san will get mad!"

"S-Silver rank! We get to go with a silver rank on our first adventure!" Warrior was stunned. Going on a quest with a Silver rank, even one with armor like Goblin Slayer, was so amazing to him that he hadn't realized they had absolutely no faith in his ability to live.

"You can still die pretty easily though, so take this gold and we'll figure out a way for you to pay us back later." Avenger said rather dryly. "Anyways, Goblin Slayer, you might want to tell Guild Girl about joining these rookies. She should have some Goblin extermination quests for you too."

"I see." Goblin Slayer said and turned to head to Guild Girl, who gave the twins a subtle thumbs up, which they returned by having glints in their eyes.

He talked to the Guild Girl about the other goblin quests and Avenger and Shielder pushed Priestess's back.

"C-coming!" Priestess started to follow him, and the other 3 hesitated before doing the same.

"Ne, Goblin Slayer! You better make sure to teach them properly!"

"Hoh? What'd I miss here? Another group of kids saved by owing the devils a favor?" A man in armor who walked behind them said. He was one of the experienced adventurers that the twins had gotten quite close to over their years at the Frontier.

"I...think that it's quite...fine..." his companion said. She was the one who convinced the Spearman that despite their age they were quite strong, part of the reason she asked him to let them join their quests was not their strength, but their assistance in getting Spearman's attention towards her and not other women.

"Ah well. Anyways, did you two want to join in on a quest? It's just some wild monsters out in the mountains, but it might be a good way to waste time with the current lack of missions."

The twins looked at each other. Communicated with their eyes was easy enough with their understanding of themselves and their other.

"I think we'll be fine. A few mountain-"

"-monsters aren't particularly threatening to anyone. We'll just take this time to-"

"-relax and stack up some favors from suckers, I mean, adventurers."