Shirou was walking down the hallway, minding his own business. As he did, he then heard a familiar voice calling out to him.

"Hey, Shirou!"

Shirou turned around, expecting to see Arturia behind him upon hearing her voice. However, instead of her, he saw Proto-Merlin instead.

"Oh, hey there Merlin," Shirou said.

It was then that Merlin suddenly came up to him in an instant and tugged him on the ear. "Call me Merlin onee-san!" she said with a pout on her face.

"Owowowowowowo...f-fine. Anyways, what brings you here?"

Proto-Merlin then stopped tugging on Shirou's ear. "Well, there's a small thing I need to ask from you..." she said with a sly grin on her face.

Shirou gulped upon seeing Proto-Merlin's sly grin. "Oh boy. That face she's making...it reminds me of the same smile Merlin would do when he's planning on pranking someone..." Shirou then calmly recomposed himself. "So, what are you asking me to do Merlin...onee-san..." he said with a bit of struggle at the last part of the sentence.

Proto-Merlin's sly grin grew even further. "Well...follow me and you'll see! Now come on!" As she said that, she then grabbed Shirou's arm and suddenly ran in the hallway, dragging him along.

"Whoa! Merlin! Slow down!" Shirou yelled.

"Sorry Shirou, but this is important on my life!" Proto-Merlin replied.

Shirou let out a small sigh. "Really? I'm not sure after seeing that grin on your face..."

After many minutes of Proto-Merlin dragging Shirou around in the hallways of Chaldea, she finally came towards a stop when she and Shirou arrived in front of a room. "Um...Merlin onee-san, just where are we?"

"Here!" Proto-Merlin said as she suddenly threw Shirou into the room, catching him by surprise.

"What the-?!"

In an instant, Shirou was thrown into the room. When he did, he then heard the doors shut behind him. "What the-Merlin!" Shirou yelled.

"Sorry, but this is very important for him you know!" Proto-Merlin yelled from the other side of the room. "Anyways, have fun in there with him!"

Shirou was confused for a moment about what Proto-Merlin said until he looked behind him. As he did, he saw Arthur Pendragon, who was just sitting there.

"H-Hey there Shirou...this is quite the predicament we are in right now, aren't we Shirou?" Arthur said with a chuckle.

Shirou let out a small sigh at the situation he was in now. "You can say that again..." Shirou replied. "Anyways, I supposed that you got here because of Merlin?"

"Which Merlin? Your Merlin or my Merlin?"

"Your Merlin."

Arthur let out a sigh. "I see. Well, you're not alone in this as well."

Shirou immediately knew what Arthur was talking about. "Let me guess, my timeline's counterpart of your Merlin dragged you into this room as well?"

"Yes."

Shirou sighed again. "I swear, what's with the two Merlins and their pranks?"

"Honestly, I have no clue as well. It's as if they were made to completely cause mayhem wherever they go. To be honest, the moment I saw my version of Merlin here in Chaldea the first time when she got here, I immediately had a bad feeling about what was going to happen next."

"You can say that again. And I suppose that when your version of Merlin met my version of Merlin, that bad feeling grew even further to the point where your worst fear came true?"

"Yup."

"Figures. Anyways, how long have you've been here?"

"About a few minutes I think."

"Any way to get out of here?"

Arthur shook his head. "Not one that I can think of at the moment."

"I see. Well, I guess for the time being that until someone tries to find us, we'll stuck here together for the time being."

"Yeah. By the way, when I was thrown into this room by your world's version of Merlin, he also gave me this," Arthur said as he revealed something from his pockets. The items he revealed were paper boxes that contained a set of cards in each of them. Each of the boxes contained artwork of an anime character and two cards in the front, and they were different as well. And they weren't normal playing cards either. One of the boxes shown a card that had artwork of a knight wearing a cape and wielding a sword while the other card shown another knight in heavy armor wielding a giant sword while riding a pegasus. Meanwhile, the other box had a different character and the two cards that were featured in the front were two dragons of different design.

Shirou examined the box sets Arthur was showing to Shirou. "Hm? Cardfight Vanguard G? These look like trading cards, but they don't look like any cards I've ever seen before. And the fact that the amount of text that's on the cards...looks like there some strategies and gimmicks involved..." he thought as he looked at the box. "Hey Arthur, do you know what are the items my world's version of Merlin gave you?"

"Oh these? I assume they're playing cards, like the ones people would play with," Arthur replied. "Now that I'm thinking about it, your world's version of Merlin gave me these two boxes of cards to play with someone while my world's version of Merlin dragged you here so I can play with someone with these cards."

"Seems so. And I have a good feeling that this was both my Merlin's and your Merlin's plan..." Shirou said.

"Definitely," Arthur said with a sigh. "Well, for now, until someone tries to find us and opens the door, how about we play this for a bit?" he suggested.

Shirou thought about Arthur's suggestion and replied, "Sure. I don't mind. Although which box should we choose?"

"Well, I could go for the blue box if you don't mind."

"Okay. Guess I'll go for the red box then."

Arthur then gave Shirou the red box and they sat down on the ground, opening the boxes. As they did, they unpacked everything that came with the box. Each box contained 56 cards, a storage box, card sleeves, a special deck holder, a fighter's counter, a clan cards, two promo cards, a paper playmat, and a manual guide.

Shirou and Arthur then grabbed the manual guide from their boxes and read it over, learning the rules, skills, units, and everything else. As they were done reading their manuals, they brought out their cards and shuffled them around, putting them in a stack when they were done shuffling. As they did, they then unfolded the paper playmats. Afterwards, they then placed their grade zero cards onto the middle of their playmats while placing their decks and g-zone cards on the sides.

"Okay. Now that we got ourselves ready, should we play rock-paper-scissors to decide who goes first?" Shirou asked.

"Good idea," Arthur replied. Soon, Shirou and Arthur began to play rock-paper-scissors to decide who goes first. As they did, Arthur won with paper. "Well then, looks like I go first."

"Seems so," Shirou said as he soon began to draw five cards. Arthur then did the same thing as well. "I'm good with what I have. How about you?"

"Hm...I'm okay with what I have as well."

"Very well. Let's begin."

Soon, both Shirou and Arthur placed their hand on their forerunner cards. As they did, they said one phrase that starts the game.

"Stand Up! Vanguard!"

Arthur drew a card. "I ride Little Tactician, Marron," he said as he placed a card down in the middle of his playmat. "Blue Scud, Barcgal moves to the back." Arthur said as he moved the mentioned card to the back. "Turn end."

"Draw. I ride Lizard General, Conroe," he said as he placed a card down in the middle of his playmat. "Lizard Hero, Undeux moves to the back," Shirou said as he moved the mentioned card to the back. "Boosted by Undeux, Conroe attacks your vanguard," he said as he moved his cards sideways.

"No guard," Arthur said.

"Drive trigger check," Shirou said as he flipped over the top card of the deck. "No trigger," he said as he placed the card into his hand.

"Damage trigger check," Arthur said as he checked the top card of his deck. "No trigger," he said as he placed the card into the damage zone.

"Turn end," Shirou said.

Arthur then drew a card from the top of the deck. "I ride Blaster Blade," he said as the placed a card on top of the card in the middle. "And then I call Knight of Virtue of, Bedivere," he said as he placed a card on the right side of blaster blade. "I attack your vanguard with my vanguard boosted by Barcgal."

"No guard," Shirou said.

"Drive trigger check," Arthur said as he checked the top card of his deck. As he did, he let out a small smirk. "Critical trigger. I give the power to Bedivere and the critical to Blaster Blade, which means you take two damage."

"Very well. Damage trigger check," Shirou said as he checked the top cards of his deck. As he did, the top two cards didn't have any heal triggers. "No trigger," he said as he placed them into the damage zone.

"All right. Now Bedivere attacks your vanguard."

"No guard. Damage check." Shirou then checked the top card of his deck. "Heal Trigger. I give the power to my vanguard and heal one damage," he said as he placed one card from his damage zone into the drop zone and placed the heal trigger into the damage zone.

"Turn end," Arthur said as he was done with his attacks.

"Stand and draw," Shirou said as he drew a card from his deck. "I ride Emperor Dragon Knight, Nehalem. And then I call Armor of the Flame Dragon, Bahr," he said as he placed the cards down. "Then he attacks your vanguard boosted by Undeux."

"No guard."

"Drive trigger check," he said as he checked the top card of the deck. "Draw trigger. I give the power to Bahr, and I draw."

"Damage trigger check," he said as he checked the top of his deck. "No trigger." He then placed the card into the damage zone.

"All right. Now Bahr attacks your vanguard."

"I guard with Wingal Youth," he said as he placed the card in the guardian circle.

"Turn end."

Arthur then placed the card into the drop zone and drew a card from the top of his deck. "I ride Blaster Blade Exceed. And I activate its skill. I retire one of your rearguards, and the one I'm choosing is Armor of the Flame Dragon, Bahr," he said as he flipped over a card in his damage zone. Shirou then placed Bahr into the drop zone. "Boosted by Barcgal, Blaster Blade Exceed attacks your vanguard."

"No guard."

"Drive trigger check." Arthur then revealed the two cards that were on top of his deck. "No trigger."

"Damage check," Shirou said as he checked the top card of his deck. "No trigger as well."

"Bedivere attacks your vanguard."

"I guard with Margal."

"Turn end."

Shirou then drew his card. As he did, he then sparked a conversation. "So this is Cardfight Vanguard...I'm starting to get interested in this..." he said with a smirk on his face.

"Me too. I've never felt this excited and competitive for a while now..." Arthur said with a smirk on his face as well. "And honestly, I don't feel like losing right now!"

"Well...so do I! I ride Dragonic Overlord, The Legend!"

Merlin and Proto-Merlin were walking down the hallway together, spreading fear throughout the hallways of Chaldea because of their fearsome reputations as scary pranksters.

"Really? That's why he's called Queen Shirou?" Proto-Merlin asked with laughter in her voice.

Merlin beamed at his female counterpart's question. "Exactly! Because of Mordred's suggestion, she came up with the idea of Queen Shirou! Not only that, but she also came up with the idea of calling Shirou mother!"

Proto-Merlin's laughter grew even further. "Wow! Now I'm glad you didn't tell me any of this earlier! I didn't know it was going to be this hilarious!"

"Indeed!"

As Merlin and Proto-Merlin continued walking down the hallway, they passed by the same room that they threw both Shirou and Arthur in and overheard a conversation both were having.

"Really? Gilgamesh was there in your world's version of your Holy Grail War?" Shirou asked.

"Yeah. While he was arrogant and was an Archer class servant, he was completely different from the one that is here right now," Arthur replied.

"How so?"

"Well, for starters, his noble phantasm wasn't that sword of his. Rather, he used two swords that can turn into a bow when combined. He also didn't have the Gate of Babylon, but he did have something like that at least."

"I see. Who else was in the Tokyo Holy Grail War?"

"Well, there was Perseus as Rider, the younger version of Cu as Lancer, Hercules as Berserker, and that's all I know of. Assassin and Caster, well, I didn't know who they were," Arthur replied as he drew a card. "Anyways, stride generation!" he said as discarded a card into the drop zone and pulled a card from the G-Zone. "Divine Knight King, Alfred Holy Saver!"

As Shirou and Arthur were continuing their game, both Merlin and Proto-Merlin let out a smile as Proto-Merlin's plan worked. "Well then, looks my plan worked perfectly. Thank you for your help, me."

"No problem. It's a good thing I bought those starter decks on sale. That way, things won't get boring between the two. Speaking of which, should we check on them to see how they're doing?"

Proto-Merlin let out a huge smile. "Well then. Let's see..."

Both Merlin and Proto-Merlin then headed into the room to see what Shirou and Arthur were up to. And to their surprise, both of them didn't notice them coming into the room.

"I attack your vanguard with Divine Knight King, Alfred Holy Saver!"

"Perfect guard with Flame of Tranquility, Aermo!"

"Triple Drive! I got a critical trigger! I give all the effects to my rearguard!" he said as he placed the drawn cards into his hand. "Blaster Blade Exceed attacks your vanguard!"

"I guard with Kenran Master, Gojo and Seiten Master, Goku!"

"Twin Drive check!" Arthur let out a small sigh as he checked the top two cards from his deck. "No trigger. Turn end."

Shirou let out a small sigh as well. "Wow. That was close, you nearly got me there. Especially with Blaster Blade Exceed..." he said.

Arthur let out a chuckle. "I should say the same thing to you. When you used Dragonic Overlord, The Legend's Generation Break ability, I thought I was a goner. There's also the fact that you used your rearguards' abilities to retire my rearguards! You kept wiping my units off the board!"

"True..."

"Um...I see that both of you are having fun here," Proto-Merlin interrupted.

Shirou and Arthur heard Proto-Merlin's voice and turned to see both Merlin and Proto-Merlin looking at them with smiles on their faces. "Hey there Merlin," Arthur said.

"Hey there Arthur. I see that you're having fun with Shirou over there? Especially with those cards I gave you?" Merlin asked.

"Yeah Merlin. It did help pass the time. We also did have a few conversations along the way."

"Really? What kind of conversations?"

"Well, some of them were the differences between the holy grail wars we were in and a few other personal things," Shirou said.

"I see," Proto-Merlin said as she looked at the card fight the two were having. On Shirou's side of the field was Dragonic Overlord, The Legend in the middle, Berserk Lord Dragon on the right, Armor of the Flame Dragon, Bahr on the left, Lizard General, Conroe behind Berserk Lord Dragon, Dragon Parner, Monica behind Dragonic Overlord, The Legend, and Spear of the Flame Dragon, Tahr behind Armor of the Flame Dragon, Bahr. On Arthur's side of the field was Blaster Blade Excced, Blaster Blade Exceed on the Right, and Star Hope Trumpter on the Left.

Both of them have six cards in their hand. However, Shirou has five damage while Arthur has four damage.

"Hey, do you mind if me and my male counterpart watch you play?" Proto-Merlin asked.

"Eh? Well, sure, but don't pull anything on us."

"Very well. We won't do that," Merlin said.

Arthur let out a small sigh. "Anyways, let's get back to the game."

"Yeah," Shirou replied as he drew a card from his deck. "Stride generation!" he yelled as he placed a card into his drop zone and pulled a card from his g-zone. "Supreme Heavenly Emperor Dragon, Dragonic Overlord, The Ace!"

Both Merlin and Proto-Merlin were a little shocked at the name of the card. "Supreme Heavenly Emperor Dragon, Dragonic Overlord, The Ace? That's a bit too long for a name, even for my taste..." they thought in unison.

"I activate it's skill! I put two cards in my damage zone face down and flip up one card with the same name as my vanguard from my g-zone. Since I have two or more cards in my g-zone, my vanguard loses one drive until the end of my turn. However, it is that at moment that I activate Conroe's ability! I retire it from my field so that whenever my vanguard attacks, I get to flip over two facedown cards in my damage zone."

Arthur was a bit shocked upon hearing Shirou's explanation. "Oh boy, this can't be good..."

"Here I go! Boosted by Tahr, Bahr attacks your vanguard!"

"I guard with Nova Knight, Llew!"

"Boosted by Monica, The Ace attacks your vanguard! At this moment, I activate Monica's skill! Since she is boosting a flame dragon, the boosted unit gains an additional 3000 power! Not only that, but because my vanguard is attacking, I activate Berserk Lord Dragon's skill and retire Star Hope Trumpeter!"

"Tch!" Arthur muttered as he put Star Hope Trumpeter into the drop zone. "Perfect guard with Bringer of Divine Grace, Epona!"

"Twin Drive!" Shirou said as he checked the top two cards. "I got a critical trigger, and I give all of the effects of my vanguard!"

At that moment, Merlin and Proto Merlin were confused with what just happened. "That's odd. Why did he give all of the effects of the vanguard?"

Meanwhile, Arthur was having a different reaction. "Oh no..."

"It is at this moment that I activate The Ace's skill! After my vanguard attacks, I discard a card with overlord in its name along with two other cards, and it re-stands itself and gains an additional 5000 power!"

At that moment, Merlin and Proto-Merlin immediately knew what was going to happen now. "Oh boy, this can't end well for Arthur..."

"The Ace attacks your vanguard! At this moment, I activate Berserk Lord Dragon's skill and retire your other rearguard!"

"Not again..." he thought as he removed his last rearguard from his field. "I guard with Pink Comet, Flogal, Nova Knight, Llew, and Wingal Youth!" he said as he used up nearly all of his cards in his hand. "As long as he doesn't get a trigger, I should be fine..."

"Twin drive check." Shirou then checked the top two cards. The first one didn't have a trigger, which made Arthur sigh in small relief.

However, the second card was a trigger, and a critical trigger of all things.

"Critical trigger. I give all the effects to my vanguard," Shirou stated.

At that moment, Arthur knew his fate was sealed and the match was over. "Damage trigger check..." he said as he checked all three cards from the top of his deck.

And they were not heal triggers.

"Well, it's my loss," Arthur stated calmly.

Shirou let out a sigh of relief. "Wow. That was close."

"You can say that again. I didn't expect to see two critical triggers in your drive checks. Of course, when I saw you stride into Supreme Heavenly Emperor Dragon, Dragonic Overlord, The Ace, I knew I was going to be in a rough ride because of its skill."

"Indeed. Anyways, that was a great game, Arthur."

"Yeah. Want to go again?"

"Yeah. This time though, we're switching decks."

"I agree with that."

As Shirou and Arthur were switching decks, Merlin and Proto-Merlin let out a smile on their faces. "Well then, looks like I unlocked a new hobby for them."

"It seems so. However, at least my plan to get Arthur to have some fun with his friends worked," Proto-Merlin replied.

"Indeed."

"Stand Up, Vanguard!" Shirou and Arthur yelled.

Omake

Shirou was walking down the hallway, minding his own business. As he did, a certain servant appeared in front of him.

That servant was Ozymandias, also known as Ramesses II.

For a moment, both sides didn't say anything until Shirou started the conversation.

"Um...can I help you?" Shirou asked.

It was then Ozymandias brought out something from his robes, and much to Shirou's surprise, it was a Shadow Paladin Vanguard deck.

"Hahahahahahahaha! Emiya Shirou! My name is Ozymandias! The King of Kings! And I challenge you to a vanguard fight upon hearing your victory against the King of Knights in the game!"

At that moment, Shirou was completely confused. "What?"

Author's note: If anyone got the reference in the omake, you get a cookie.