Disclaimer- I do not own Bleach.

A/N- This is a sequel to Enemy in Soul Society and although reading it isn't strictly necessary, if you haven't read it then there are a few things in this fic that won't make sense so keep that in mind. Read and review.

Understanding

Chapter One- Hinamori's Decision

Captain of Squad Ten, Toushirou Hitsugaya was walking across the Seireitei, on his way back to the Squad Ten barracks, when he saw someone approaching him from the opposite direction. And as he got closer to the person Hitsugaya saw that it was the acting captain of Squad Three, Izuru Kira.

"Captain Hitsugaya," Kira called out once he was within easy speaking distance.

"What is it Kira?" Hitsugaya asked, noticing the concerned look on Kira's face.

"Have you seen Momo?" Kira asked, coming to a stop in front of the young captain of Squad Ten.

"Not recently," Hitsugaya replied. "Why?"

"Because Head Captain Ukitake summoned all of the acting captains to his office for a meeting," Kira said. "But no one can find Momo."

Hitsugaya shook his head. He really hoped that Hinamori wasn't going to make him lament the fact that he'd recommended her to be the acting captain of Squad Five. "Let me take these papers back to my office and then I'll see if I can find her."

Kira bowed. "Thank you sir."

Hitsugaya nodded and continued on his way toward the Squad Ten barracks. When he reached the office he found his vice-captain Rangiku Matsumoto asleep on the sofa, which didn't really surprise him. She could usually be counted upon to avoid doing work and this was one of her favorite ways of doing it. Walking across the office Hitsugaya placed his stack of paperwork down on the desk and as he did so he saw a piece of paper that had most assuredly not been there when he'd left the office earlier. Picking up the piece of paper, Hitsugaya's eyes widened as he read the words that were written upon it, written in a familiar hand.

Toushirou,

I'm really sorry for what I'm about to do since I know that it will most likely cause you pain but I feel that I have to do this for my own peace of mind. I'm going to travel to Hueco Mundo and confront Captain Aizen. Please understand Shirou-chan, I have to do this. I have to know why he betrayed us, why he betrayed me.

All my love,

Momo

There were small patches of the paper that were discolored, as though Hinamori had been crying when she'd written the letter.

"Idiot!" Hitsugaya growled, crumpling the piece of paper he was clutching in his hand. "What the hell are you thinking? He already tried to kill you once, what the hell makes you think this time will be any different?"

The sound of Hitsugaya's angry voice roused Matsumoto from sleep and she raised up and gazed over at her captain. She immediately noticed the angry look in his eyes and there was a questioning look in her own eyes as she asked, "Captain, is there something wrong?"

"You could say that," Hitsugaya growled. "Hinamori's gone to confront Aizen."

Matsumoto gasped.

"I'm going to see Head Captain Ukitake," Hitsugaya said, turning on his heel and heading toward the door. "Stay here and wait for my return."

"Yes sir," Matsumoto said. She recognized the look on her captain's face and knew that he was not in the mood for disobedience or argument.

Sliding the door open Hitsugaya strode from the office and made his way across the Seireitei, to the Squad One barracks. Still clutching the balled up letter in his clenched fist Hitsugaya knocked on Ukitake's office door. "Captain of Squad Ten Toushirou Hitsugaya requesting a meeting sir."

"Enter," Head Captain Ukitake called out.

Hitsugaya slid the door open and entered the office. His eyes quickly sought out and found Ukitake who sat behind the desk doing paperwork. The Head Captain glanced up as Hitsugaya walked across the room and came to stand in front of him. "Toushirou, what brings you here?"

"Hinamori," Hitsugaya said simply.

That statement, coupled with the angry expression on Hitsugaya's face and the worry hidden in his voice, served to gain Ukitake's full attention. "Do you know where she is?"

"No," Hitsugaya replied honestly. "But I know where she's going."

Unclenching his fist Hitsugaya un-crumpled the note that Hinamori had left for him and handed it to the Head Captain. Ukitake took the piece of paper from Hitsugaya and scanned its contents, his eyes widening in disbelief. "When did you find out about this?"

"Right before I came here," Hitsugaya replied. "Kira asked if I'd seen Hinamori and when I went to my office I found this note. Then I came here."

"This is not good," Head Captain Ukitake said.

"I know," Hitsugaya said. "Which is why I would like your permission to go after her."

"I think that would be ill advised Toushirou," Head Captain Ukitake said, his tone serious. "We must. . ."

However Hitsugaya wouldn't find out what they must do for Head Captain Ukitake's words were cut off by a sudden knock on the door. "Head Captain Ukitake!"

Recognizing the voice of his third seat Sentaro, and hearing the frantic note in his voice, Ukitake called out, "Enter."

The door burst open and both Sentaro and his co-third seat Kiyone hurried into the office.

"Head Captain Ukitake," Sentaro called out as he and Kiyone hurried across the office. "A group of huge Hollow have broken into the Seireitei and are giving the gate keepers some trouble."

Ukitake got quickly to his feet and turned to face Hitsugaya. "I must attend to this matter. Toushirou, we'll have to continue this discussion at a later time."

And with that Head Captain Ukitake turned and followed his subordinates out of the office. Hitsugaya watched as Ukitake left the office and then he too departed. Walking back to the Squad Ten barracks, Hitsugaya entered his office where he found Matsumoto awaiting his return as ordered.

"Will you tell me what's going on now sir?" his vice-captain asked.

Hitsugaya nodded. "Like I told you before Hinamori's left Soul Society and plans to travel to Hueco Mundo in order to confront Aizen."

"And what did the Head Captain have to say?"

"Our meeting was interrupted," Hitsugaya said. "But I have to go to Hueco Mundo and retrieve her before something bad happens to her. And I'm leaving immediately. I just stopped by here because I thought you had the right to know."

"You can't be serious captain," Matsumoto said.

"I'm dead serious," Hitsugaya said, the tone of his voice leaving no question as to his intentions.

"Then I'll come with you sir," Matsumoto offered, jumping to her feet.

"No," Captain Hitsugaya said, his tone serious. "I forbid you to come along and I also forbid you to follow me. This is my decision and I'm going alone."

And with that Hitsugaya turned and walked away, leaving Matsumoto to stare at his retreating back, a concerned look in her eyes.

Leaving the Squad Ten office Hitsugaya made his way to the gate that surrounded the Seireitei and then entered the Rukongai. This would be the best place to depart from since no one was likely to feel his reiatsu from this distance with the Hollow invasion going on. He wasn't worried about his comrades, they could take care of a few measly Hollow, his concern was all for Hinamori who seemed determined to get herself killed.

"Idiot," Hitsugaya muttered as he summoned the Senkaimon. The doors of the gate opened and Hitsugaya traveled through it to the world of the living. He'd been thinking about his course of action ever since he'd read Hinamori's letter and had decided that the best way to get into Hueco Mundo would be to force someone to open the portal in the world of the living and then follow them inside.

This having been decided Hitsugaya made his way to a secluded section of the world of the living and once there he released a tremendous burst of reiatsu. And it wasn't long before the bait was taken. A huge Arrancar appeared, glaring at Hitsugaya with evil intent plainly evident in its eyes.

"Well that didn't take long," Hitsugaya thought to himself as he pulled Hyourinmaru from its sheath.

The Arrancar opened its mouth and a bright light began to build. The beast intended to use a Cero against the young captain, who did not look even remotely intimidated by this move. Hitsugaya had spent a couple of months in the world of the living after he'd been attacked by a pair of rogue Shinigami and during that time he'd grown accustomed to battling Arrancar on a daily basis. And compared to a few that he'd faced this one's power didn't even register.

Hitsugaya unleashed Hyourinmaru although he had to be careful to wound the Arrancar without actually killing it. He needed the beast alive and scared in order for his plan to succeed. The dragon of ice circled Hitsugaya once and then flew directly toward the Arrancar. The Arrancar roared its displeasure and raced toward the young captain, dodging the dragon. Hitsugaya raised his sword and, leaping into the air, sliced the Arrancar across the chest. Then, turning in mid air, he quickly sliced the beast across the back.

Landing lightly on the ground Hitsugaya raised his zanpaktou, ready for another attack. However another attack did not come. Turning away from Hitsugaya the Arrancar summoned a portal, prepared to retreat back to Hueco Mundo.

A smug expression on his face Hitsugaya leapt into the air and, using his flash-step, quickly followed the Arrancar into the portal. Then, upon arriving in the world of the Hollow, the young captain quickly destroyed the Arrancar with one swing of his sword.

"Now to find Hinamori," Hitsugaya said, sheathing his sword.

"My Lord Aizen!"

Seated upon his throne Aizen gazed down at the Espada who'd just barged into his throne room. "What is it Yami?" he asked imperiously.

"There's another intruder in Hueco Mundo," Yami reported, kneeling in front of Aizen. "Some kid with white hair just followed an Arrancar through the portal."

"I'm already aware of this," Aizen said, gesturing toward another Espada, who stepped from the shadows.

"Ulquiorra!" Yami exclaimed.

The emotionless Espada said nothing and his expression did not change.

"Yami," Aizen said. "You and Ulquiorra are both dismissed."

The two Espada bowed to their master and then turned and left the throne room without another word.

"Would you like for me to go and take care of the boy Lord Aizen?" Gin Ichimaru asked from his position below. "I have a score to settle with him after all."

"That will not be necessary Gin," Aizen said, an unconcerned expression on his face. "Hitsugaya's arrival doesn't change anything and we will not interfere. Watch their progress but do nothing more."

"Yes Lord Aizen," Ichimaru and Tousen both said.

Her zanpaktou drawn Momo Hinamori made her way across Hueco Mundo. She'd been battling Arrancar since her arrival and the fights had left her a little out of breath.

"Toushirou wasn't kidding about these guys," she thought to herself, taking a couple of a deep breaths. "They're tough."

Thinking about Hitsugaya caused tears to appear in Hinamori's chocolate colored eyes. There was no doubt in her mind that her childhood friend was furious with her because of the decision she had made however she had to know. She had to know whether Aizen had always been evil or whether something had happened that had caused him to turn against Soul Society. This question had been haunting her since she'd emerged from the coma induced by Aizen's attack and she had to find out the answer.

The attack on Hitsugaya had served to occupy Hinamori's mind and keep her from dwelling on the problem however once the attackers had been found and the traitor killed she found that her thoughts kept returning to Aizen. Even being named acting captain of Squad Five hadn't been enough to keep her thoughts away from her former captain.

Deciding that in order to keep her sanity she would have to face Aizen and confront him about his treachery, Hinamori made her decision to travel to Hueco Mundo. Once she reached this decision Hinamori knew that there was no other way however she also knew that she couldn't tell any of the others about it or they'd try to stop her either by talk or force. She couldn't allow that to happen however she knew that she couldn't leave Hitsugaya in the dark. He was her best friend and after everything she'd already put him through she knew that she just couldn't do that to him. However she also knew that she couldn't tell him in person since he'd be the first to try and stop her so she'd decided to leave him a note explaining the situation and begging for him to understand.

"Please understand Shirou-chan," Hinamori thought to herself as she continued her trek across Hueco Mundo.