Mercer: Between Different Worlds

Kurosaki Clinic 

"Hope you come and visit again, ma'am"

Isshin Kurosaki had just finished diagnosing one of his regular patients. He just greeted them at his clinic. 

"It's been nothing but dark clouds and a drizzle" The somewhat 40-year-old somberly looked at the fairly grey sky. 

This usually tells an ominous foreboding, or a sign of someone's demise

As he's about to return to his office, his phone suddenly rang. He immediately picked it up to answer 

"Kurosaki Clinic, this is Isshin Kurosaki speaking"

"Yahhh... I finally managed to get a reception here" an aloof voice suddenly came out in the receiving end. Isshin pinched the corner of his eyes in annoyance 

"Oh, it's you Urahara. I haven't seen you in your store lately, where are you now?"

"I'm licking my wounds and patching things up in Hueco Mundo"

Isshin was surprised. Never had he thought that Kisuke Urahara would end up in Hueco Mundo ever since their battle with Aizen.

"Hueco Mundo? Wait, what are you even doing there in the first place?"

"Your idiot son asked for my help, said that Nel came falling here talking about an army of Quincy decimating the place"

...

There was total silence after what Urahara told him. Both men know what this means 

"So it began then. How's Ichigo?"

"He faced him, and there's no surprise he was very outmatched. However, you really need to listen closely. Mayuri called me about how the Wandenreich invaded the Soul Society, and from what he told me it seems that we have another player in the mix."

"Another player?"

"Yes. Right when Yhwach had his zanpakuto shattered in half, something happened that made me doubt what Mayuri told me."

"And that is?"

"His zanpakuto... He turned into a human being or something, and managed to outmatch Yhwach for a short period of time"

Isshin's jaw dropped. He had heard of zanpakuto spirits channeling their human form for a brief period of time, but never did a zanpakuto transform into a human form directly. What's more shocking for him is the fact that he was able to go toe to toe with Yhwach himself...

... and surprisingly won by a long shot 

He had known Urahara and his carefree nature for more than a hundred years. The tone in his voice telling him all that stuff, tells him that he was serious. 

"Oi Urahara, tell me you're lying about all that stuff"

"That's why I'm finishing things up here in Hueco Mundo. I'm going to Mayuri himself, and if what he said is true, then we may have a wild card setting things up in this war–"

Out of the blue, Isshin felt a faint sense of strong spiritual pressure from afar 

"Sorry Urahara, gotta check something out"

He immediately hung up on Urahara, then took on his coat hanging by the chair.

"Karin, Yuzu, there's somewhere I have to go first. I trust that you two can take care of the clinic for me." Isshin gave his instructions to his two daughters before he left the clinic 

The pressure ain't that far. From where I felt it, seems likely to the north 

Karasu River, 10 minutes later

Isshin reached the epicenter of the spiritual pressure he felt earlier. Countless public workers have flocked to the location. From the looks of it, this t was a scene of utter devastation. 

A number of buildings have been cut in half. Some were smashed through. A few deep craters were present at the river

What in the name of Adyneus happened here?

Isshin passes himself off as a volunteer, allowing him to look further. He held himself together as he passed by many people suffering moderate to severe injuries, but he wasn't prepared for what came next; he reached the place where dead bodies had been lined up.

Some were mutilated beyond recognition...

Some had their limbs and heads missing...

Some have been charred...

Some had their faces twisted in fear...

Some...

Some...

Some...

...

Isshin couldn't help but nearly throw up at the sight of those poor victims. He had been used to death as a former Soul Reaper and Captain of the 10th Division, but never before he had seen this on a gruesome scale.

Who could've done this? They're monsters...

He had regained his composure when he suddenly saw a familiar figure carried in an ambulance. He rushed towards it

It was Lisa Yadōmaru and Hiyori Sarugaki, two former Soul Reapers who have been turned into Visored through Hollowfication. They haven't suffered any life-threatening injuries, but they were pale enough to be needing medical treatment.

"Lisa, Hiyori, are you both okay?"

"Do we look okay to you? We've been loaded here for fuck's sake." Hiyori rudely replied as she looked on the ex-Captain of the 10th Division 

"What happened there?"

Hiyori stayed silent. She doesn't want to talk about it. Lisa offered to explain everything.

"We got a call from Shinji... He told us to be on the lookout for a man in a hoodie... Then we happened to see Uryu alone by the riverbed. We were about to check on him when the man came with Ryuken"

A man in a hoodie? And Ryuken?

"A small group of quincies came and started attacking the hooded man, probably the same people who invaded Soul Society. The Ishidas were able to flee away from the riverbed. We started evacuating anyone in the vicinity... When we came back to check the battle, we just saw the hooded man standing tall over those quincies."

"Wait, the man you were told to be on a lookout won? Against those quincies? And by himself?"

There was silence among the three. Isshin understood what that silence meant, but couldn't comprehend for a second how that happened. Needing some answers, Isshin nods to Lisa, gesturing her to finish explaining 

"There was another group who came. They picked up those who had fallen in battle, but couldn't pick up the two behind the hooded man. There was a brief fight, and then... He just released his reiatsu all over the place. Thankfully we're able to hold out, but we were unable to move. Those humans... They weren't lucky" Lisa finished her explanation with a grim conclusion

Isshin gave her a pained look as he recalls having passed the row of bodies a little while ago

Then came to mind what Urahara told him on the phone about a third player

'He turned into a human being or something, and managed to outmatch Yhwach for a short period of time'

"You two, take care of yourselves" Isshin said to the two before he leaves the ambulance 

A man in a hoodie... If he's able to exert reiatsu on a greater scale then that means he's the one who defeated Yhwach and caused this mess... 

Then there's Ryuken and Uryu making contact with him. There should be a good reason why he and the Ishidas are working together...

Damn it, everything's a mess…

Karakura Hospital, present time

Mercer suddenly appeared a few feet before the Ishidas. He was carrying the unconscious Bazz-B and Bambietta in his arms when he groggily landed on his feet 

He still hadn't gotten used to the mixture of hirenkyaku and shunpo, causing him to misjudge his timing 

"There was a release of reiatsu not far from here. I presume that must be during your battle with those you think would come for my son" Ryuken coldly greets Mercer's arrival

"Pretty much, yeah" He flatly replied as he dropped both bodies to the floor.

He then turned to Uryu, who looked at him in disgust

"Now where was I? Right... my name was Alex Mercer" He reintroduced himself to Uryu 

"Yeah I heard you before. It's hard to believe that you killed six million people out of spite"

"Not really out of spite, but it's true that I killed six million people"

Uryu is appalled at how Mercer callously admits to have committed mass murder on a greater scale. He compared his attitude to that of Mayuri Kurotsuchi, one of the Gotei 13 captains he had faced before 

"Tell me, what happens now that you have shaken off your pursuers?" Ryuken interjected between them, hoping to dispel any ill intentions from his son

"Not really. For some reason, that first group appeared out of a portal, right where we are. I suspect these people have been monitoring everything around this world the whole time"

"If that's the case, why didn't they bring the whole army?"

"The only reason I can think of is pure revenge, that they're acting without their Majesty's permission." Mercer explained as he pointed to Bazz-B

"This guy was talking about his friend that I consumed the moment I came to this world. From the memories I could read, these two were childhood friends before they became Sternritters" He explained further as he transformed himself into Jugram Haschwalth 

Uryu was stunned at Mercer's transformation. For a moment, tendrils suddenly appeared from his feet up to his head, changing into a different form. As if he became a completely different person 

His face changed from a complete look of disdain, to that of an astonished one.

Seriously, who? No, what the hell is he?

"Now that this crap happened, I can't stay here any longer. They might back with the whole army looking for me"

"Ahh... I think so too. Your presence wouldn't just attract the Wandenreich. Sooner or later, the Soul Society would come hunting you down, and a few former soul reapers would also want to extend their cooperation in the manhunt" Ryuken agrees to his suggestion 

"Not to mention, there's Grimmjow Jaegejaquez. I don't know if he survived the onslaught at Hueco Mundo, but if word of your existence reaches him, he wouldn't hesitate to come here for the sake of fighting you." Uryu added, suddenly feeling the need to help him 

Grimmjow? I don't know who he is, but if he's as strong as those quincies then I'll consider taking the challenge

Uryu Ishida, huh. Poor kid, never got a chance to be raised by his own mom. I'd be calling myself a hypocrite for what I'm going to do

He and Uryu briefly exchanged glances at each other, before turning to Ryuken 

"If you were given the power to avenge your wife, would you take it?"

"Whether I get to kill Yhwach, one way or another, it doesn't matter. His death won't bring me back Kanae" Ryuken somberly gave his answer as he took a puff of cigarette 

"For you, it won't. But I'm talking about Uryu here"

Ryuken gave Mercer a glare upon him mentioning his son

"What are you suggesting?"

"Uryu shall accompany me"

...

...

"You can't be serious" Uryu answered in a shocked tone

"What makes you think I'll let you take my son under your wing?" Ryuken also voiced his refusal 

"Because the moment I saw him all by himself at the river, he's about to make a senseless gambit."

"What?" Ryuken then turned his defiant face into a shocked one as he looked at Uryu

"You really think I didn't know what you're trying to do? I know that look on your face. You're just as hell bent on getting revenge at that senile prick."

You don't know anything about me

"Tell me, what are you going to do? Sneak up and stab him in the back in his sleep?"

Stop

"You're all alone against the people I have faced at the river, and from your condition you're just going to get yourself killed. 

That's enough 

"And even if you do kill him, you do realize what'll they do to you and those who are close to you? You're only going to make it WORSE!!"

"I SAID THAT'S ENOUGH!!!"

Uryu immediately reached for his Seele Schneider in his pocket. In response, Mercer turned his arms into his claws. But before both could even attack, Ryuken punches his son in the face, knocking him down on the floor. Mercer withdrew his claws in response 

"I thought I told you not to cross with him" he gave a warning 

"You should've thought better than to side with the same man who took away everything for you. Don't forget, you still have someone relying on you." Mercer gave Uryu some advice, urging him to give up on his plan and come up with something else

Uryu wanted to rebuke his advice. However, images of his time with Ichigo came to his mind

... When they first met as rivals 

... When they fought side by side against hollows

... When he accompanied him to Soul Society to save Rukia

... When Ichigo came to visit him in the hospital 

Those precious memories of their friendship made him ponder on his intentions 

Heh... What was I thinking? If I ever tried to do that, then it would hurt Ichigo even more. Perhaps I'm stupid 

"So? Now that you found me out, what am I supposed to do?"

"The most sensible thing to do is to call for help. Right now, the Soul Society is in chaos, and Ichigo is nothing more than a broken mirror."

Uryu gave a pained look at Mercer, distraught at the condition the Seireitei is right now

"On the flip side, Yhwach is reduced to a broken man, they have lost their grandmaster, and today, I snatched away two of their formidable Sternritters from their clutches, so that makes their playing field even. So far, I'm the only person who came close to killing him, if not for my still-weakened state before"

"Guess I don't have much of a choice here, right, Dad?" Uryu looked at his father, then looked back at Mercer and finally made his decision 

"Okay. I'll go with you. But on one condition"

"Name it"

"Should you ever lay a hand on my friends, then we're done, and I'll be coming for your head, even if it kills me"

Mercer raised his eyebrows at his condition. Making him promise not to harm his friends is a bit too much of a stretch. Not to mention he is considered wanted by the Gotei 13 for what he did at the Senkaimon Palace 

"I can't guarantee you that, but I will try my best"

"That's fair enough"

Uryu and Mercer finally reached an agreement. An alliance have been forged, albeit temporarily. Ryuken could only look anxiously at what his son has set his path on

"Yo... fancy meeting you three here" A familiar voice was heard from behind 

Uryu and Ryuken could only look in horror at who had appeared to call them out. 

It was Isshin Kurosaki 

"Ryuken, Uryu, what's the meaning of this?" He demanded them answers in a calm tone, concealing the fury he had felt at the river 

"Isshin, stand down. You don't want to mess with-" Ryuken tries to reason with him, but he was angrily cut off by Isshin 

"Cut the crap, Ryuken. I think I demand to know what you two are doing working with a monster wearing human skin?"

He then turned to Mercer with a contemptuous look 

"And you, do you think I'll let you get away after what you did back there?"

Ryuken looked at Mercer in horror. He can immediately surmise what Isshin was talking about, but knowing the nature of who did it, as well as the circumstances of the situation, he can only stay silent against him 

Mercer immediately stepped in to their defense, justifying his actions in a heated exchange of words

"Well maybe you haven't known, but we were under attack by your mortal enemies you all thought were extinct. I had no choice but to act accordingly."

"Just like how you acted accordingly back at Soul Society?"

"It's their fault, not mine. I tried to explain myself and offer a helping hand, and all I got was an attempt on my life"

Mercer made his case. He tried to smooth tensions between him and Kensei, only for the latter to recklessly attack him instead. This proved too costly for Kensei, having his Bankai shattered in the process. But one thing stood out...

Even though he has slightly outmatched every combatant he met at Seireitei, he refrained from killing them instantly out of lack of information; the same reason why he spared Ryuken Ishida when he first came to the Human Realm. He had just been reborn there at Haschwalth's expense. The only time he was forced to kill was when he unleashed a weak Tendril Barrage that caught an unsuspecting group of soul reapers passing by

In addition, the only reason he killed everyone present at the Senkaimon Gate was because he can't afford to let himself be captured and turned into an experiment, which proved to be true considering Mayuri Kurotsuchi's reputation 

"Even so, your actions killed innocents living beside the river"

"You know it's pretty unfair to blame all their deaths on me when I'm not the only one fighting at that time"

"That doesn't excuse what you–"

Isshin stopped mid-sentence. There's no point trying to convince him.

"Well if there's no point talking you down, then I'll have to do this the hard way" Isshin said as he prepares for a Kidō spell

"Try me" Mercer accepts his challenge as he slightly enlarges his arm

Before the two of them can move to attack, Ryuken appears behind Isshin and points his Heilig Bogen behind him at close range. Isshin wasn't surprised at all, having figured he had used hirenkyaku to get past him

"Isshin... let them go. I'll take full responsibility." Ryuken pleaded with Isshin not to go through with the fight

"Idiot!! What are you doing?" Uryu was shocked at what his father tries to do

"SILENCE!!! YOU TWO JUST GO. I'LL HANDLE THINGS FROM HERE"

...

...

"You better have a good explanation for this, because I know you won't align yourselves with a monster without a good reason" Isshin reluctantly stands down

In response, Mercer reverts back his biomass to normal. He then nods to Ryuken as a thank you. He then turned back and lightly stomped at the floor. 

Countless small tendrils emerge from the ground a few feet from the two. The tendrils slowly rose and formed a rectangular shape, one that resembles a door.

Ryuken, Uryu, and even Isshin were in awe at what Mercer did

Incredible. From my experience, that's obviously a door to another realm, and he just summoned one with ease. 

We soul reapers have to open one with our zanpakuto. Even hollows and Arrancars needed one just to summon a Gargantua. For him to simply tap his feet and have the door appear before him...

Just what are you? Alex Mercer?

He then picks up Bazz-B and Bambietta, carrying them on each of his shoulders, before he pushes the door open.

"Let's go kid" He gestured at Uryu to enter.

Uryu made one last look at both Isshin and his father before he entered the door. Mercer looked at the both, then made a scoff at Isshin before entering the realm carrying the two. The door closes by itself before dissipating into reishi particles 

Ryuken immediately withdrew his Heilig Bogen as they left. He dared not to look at Isshin in the face. There were no words exchanged between them, yet the atmosphere was tense.

He simply walked towards the door and opened it. A nurse immediately appears before him, exhausted and panicking.

"Doctor Ishida, we need you at the ER"

Ryuken acknowledged his request and left the rooftop as soon as possible. From behind, Isshin was nowhere to be found