Disclaimer: I do not own Shingeki no Kyojin (Attack on Titan). I write this for your enjoyment only. This story takes place near the end of episode 25 of the anime and will be my personal take on Professor Hanji's revelation to Mikasa about how much she really knows about Eren and his titan-shifting abilities. It is a little AU but also possibly canon enough to have actually happened in the series. I also recommend reading the first fic in my saga 'More Than a Brother' to better understand this one. Enjoy! ;)

What He Really Is

It had been five days since the chaos that shook the community of Wall Sina had died down after the clash of titan-shifters Eren Jaeger and Annie Leonhart that ended up destroying a huge chunk of the city as well as causing mass casualties, both civilian and military. Unlike the Survey Corps, the Military Police had virtually no experience fighting titans and found themselves completely overwhelmed and unprepared for a titan attack since no one ever expected one to happen from within Wall Sina. From the look of things, it was likely that the damage would take months, if not years to repair. And while Annie was defeated, nothing could be learned or gained from her since she encased her human body in a crystal-like substance. The only thing that could be done was to seal her beneath the city where she could be guarded and watched around the clock in case there were any changes in her condition. Whether or not the girl would ever awake again was anybody's guess.

Ironically, (and unfortunately), the people were far more fearful of the titan-shifter who actually saved what was left of their city and Eren Jaeger found himself confined once more when he returned to human form, this time, to a private room of the Military Police headquarters at Stohess District where only a select few were allowed to see him. Like before, Professor Hanji was assigned to monitor his condition and recovery progress as she was the one most knowledgeable about his powers and as such, felt just as responsible for Eren as Corporal Rivialle, not that the boy wasn't dear to her personally as well. After making her latest report to her superiors about Eren's condition, Hanji sent for Mikasa Ackerman just as she had after the youth's trial months ago. This time, however, it had to be in secret since Eren was not allowed personal visits after countless people witnessed the destruction he caused in his fight with Annie. And while it was not like Hanji to defy orders, there was something she wanted to tell Mikasa, something she felt the girl deserved to know, especially after what the young pair had went through.

When she heard a knock at the door, the professor quietly opened it. She need not ask who it was for she knew only one person would visit at this late hour when the rest of the Military Police had returned home for the day. That, and the fact that she secretly gave only one person the key she was assigned to the front door of MP headquarters before telling her what time to come. As soon as Mikasa walked in, Hanji quietly closed the door behind them. The girl was wrapped in a dark cloak to avoid rousing suspicion in case anyone spotted her but she was as careful as could be in making sure she was not watched or followed when she answered Hanji's summons and made her way to MP headquarters to see Eren. While the professor was her superior, Mikasa was glad that Hanji treated her as a trusted friend and was also grateful for everything the older woman had done for Eren and herself.

"Good evening, Mikasa. Were you able to find your way here without trouble?"

"Yes, of course, professor. It wasn't hard considering that MP headquarters stood out as one of the few buildings not destroyed by Eren and Annie."

Despite the fact that what Mikasa has pointed out was no laughing matter, Hanji could not help but smile. "I know. We're also fortunate that most people will be too busy grieving or recovering from the chaos to really pay attention to what you're doing though I still recommend you be cautious. I trust you were not watched or followed coming here?"

Mikasa nodded. "I'm pretty sure I wasn't. My senses are sharp and I likely would've noticed if I was. But enough about me, how is Eren?"

The professor looked towards the bed where the young man was laying fast asleep. This was to be the second time she and Mikasa found themselves in this situation, the first being after the trial that ended up handing Eren over to the Survey Corps just months prior. This time, however, the youth was truly asleep and unaware of their presence or what they were saying, having been completely exhausted from his battle with Annie.

"To be honest, he is going to take a little longer to recover this time. It was unfortunate that Corporal Rivialle had no choice but to sever his limbs to free him from his titan body since he was too weak to do it himself then, but the good news is that they are growing back. His arms have already formed and his legs are well on their way. I believe Eren will regain consciousness by tomorrow but until his legs come back, I'm afraid he won't be able to leave his bed."

Mikasa was silent as she took this in. "I see…" she said in quietly. In no way was she complaining. Even if it did take a long time, Mikasa was grateful Eren would be able to recover his limbs then not at all. And while his combat skills were not quite on par with Levi's, Eren Jaeger was still considered to be the ideal soldier since he could shape-shift, heal quickly, regenerate lost body parts, and required only a fraction of the food normal humans did to survive. It was also likely that Eren could survive evisceration as well although Mikasa had no desire to see that tested.

Upon noticing the frown on the girl's face, Hanji's expression softened. "Mikasa, you need not worry. Eren is stronger than you think. He will pull through, just as he had before. It will take a lot more than this to kill him so please trust me and believe what I say."

Mikasa found herself surprised at the professor's words since Hanji spoke as if she knew Eren better than Mikasa herself did, at least his powers and abilities.

"How…how could you know that? I thought you said you weren't even sure if Eren was born like this or have I misheard you?"

The professor sighed as she took a deep breath. Hanji knew this was coming so she was not surprised at Mikasa's suspicions. "No, Mikasa, you have not. That is another reason I have summoned you here. I regret to say that I have not been entirely truthful to you about my knowledge of Eren's abilities but after what you have both been through, I feel that you have the right to know so long as you do not tell anyone, including Eren himself, what I am about to reveal to you."

Mikasa looked at Hanji curiously as she took in the professor's words. While she hated keeping secrets from the boy she loved, she knew she had to give Hanji her word if she wanted to know the truth about Eren's powers, if only so she could help him better control them. After considering a moment, Mikasa said "Yes, Zoe, I promise."

Hanji smiled. "Good. I will try to make this as simple as I can so that you will understand. "You once asked me if Eren was born a titan-shifter. I assure you, he was not- it was the result of genetic engineering and experimentation…by Doctor Jaeger himself."

Mikasa stared at her superior in shock as if her mind refused to compute what she had just heard. "How could you know this? I know my foster father was well known in our community but have you even met him?"

"More than that, Mikasa. Not only did I know Doctor Jaeger, he was also my mentor and his wife was a friend of mine as well. Eren does not know this, but I was there the night he was born. I even assisted in his birth alongside his father. I was sixteen years old. That's why when I saw him at the trial, I knew right away who he was. And when I learned about his titan-shifting abilities, it wasn't too hard for me to put two and two together for Doctor Jaeger was among the most knowledgeable about the titans. Almost everything I know about them, I learned from him. He taught me so well that I was able to become chief science officer of the Survey Corps is less than two years after I enlisted."

"And how did he know so much about the titans? Or how to create one for that matter?"

"That I truly do not know. He did tell me that before he married Eren's mother, he secretly traveled outside the walls via underground tunnels, something that has been strictly forbidden by the government since the walls were built over a century ago. When I was a child, I was told that all that was left of humanity are behind these walls but Doctor Jaegar seemed to think otherwise. He obviously didn't let the threat of danger and death stop him from exploring the outside world. My guess was that he might have met humans who knew the titans better than we do living outside the walls and learned from them even though he has never made it clear to me if that was the case."

Mikasa took another look at the comatose Eren before asking "How did he do it? And why?"

"Like I said, genetic engineering and experimentation. Likely from the time Eren was born until he was ten years old. It was something that had to be done slowly over a long period of time in order for his body to adapt."

"And I take it his mother knew nothing of this?"

"Likely not. I highly doubt Carla would have allowed it if she had known."

"And what about Eren himself? You said his father altered him over a period of ten years. If that is true, then how could Eren not know about his own powers until he was swallowed by a titan during the Battle of Trost?"

"I believe that the experiments might have damaged and distorted his memories. That is the only plausible explanation I can think of."

"But how was Doctor Jaeger able to keep it a secret from Eren's mother and myself for so long?"

The professor raised an eyebrow. "That's a very good question, Mikasa. How do you think he did it given that you yourself lived with the Jaegers for some time before Wall Maria fell?"

Mikasa was about to say she had no idea before the thought struck her and she remembered the times Doctor Jaeger would ask Eren to accompany him alone on educational 'field trips' that would last two to three days and how they would always return home with young Eren feeling exhausted and unable to remember exactly what happened or what he did. The excuse his father gave Carla and Mikasa was that Eren was simply tired from the all hunting, scouting, and studying they did and she did not think anything of it until now.

Hanji seemed to have come to that exact same conclusion as well before saying. "Now do you understand, Mikasa?"

"Ok, so now I'm pretty sure I know how. But whyEren of all people?" As she asked this, Mikasa could not help but feel appalled and outraged at how Doctor Jaeger, the man who raised them both, could subject his own son to such a barbaric experiment, knowing what he could become. The experiments were exactly that, experiments with uncertain results. For all he knew, the good doctor could have turned Eren into a full-blown titan without any way of bringing him back.

"Mikasa, you must be logical. Do you really think anyone would willingly allow their child to be made into a titan-shifter? Who else could he have used but his own son?"

"But why? Why did he do it?!"

"I really wish I could answer that, Mikasa. But I'm afraid the only person who can is Doctor Jaeger himself. And he has not been seen since the fall of Wall Maria. Many believed he perished in the attack when the wall was breached but no one actually saw him killed and his body was never found and so his death remains unconfirmed. He may be alive somewhere but we've yet to find any evidence of that…"

"I understand… if he is alive and if I do see him again, I will demand to know how he could do this to Eren. I deserve to know and so does he!" It took all of Mikasa's effort to keep from shouting in her anger even though there was nobody else around and Eren was so comatose that he probably wouldn't be able to hear her anyway.

In response to Mikasa's outburst, the professor gently took her by the shoulders and looked into her blue- grey eyes in an attempt to calm her.

"Mikasa, I understand how you feel. But you must also look on the positive side as well. Was it not Eren's titan powers that saved his life and yours time and again? Given his reckless nature, he would have likely perished a long time ago without them. And need I say that you yourself might have perished as well had he not been there for you during the Battle of Trost?"

Mikasa fell silent as she calmed down and took in the professor's words. "You're right, Zoe. I'm sorry, I didn't think."

Hanji shook her head as she gently placed her hand upon her subordinate's shoulder. "It's all right, Mikasa, there is no need to apologize. It's only natural you would be upset since you care for Eren so much. He is very lucky to have a friend like you now that his family is gone."

"I feel luckier to have him…" Mikasa corrected. "One other thing I don't understand: If you knew Eren since he was born, how is it that he did not know you until after his trial?"

The professor smiled and gave a small laugh. "Well, the reason for that is because I joined the Survey Corps when Eren was only three, long before he was old enough to remember me. And my duties over the years kept me so busy, I was not able to pay my old friends, the Jaegers, any visits. But before I enlisted, I used to visit his parents and play with him often when he was little, you should have seen him then, he was very sweet and darling before dark times fell upon him."

"And you never told Eren you knew his parents?"

Hanji sighed. "It might have been difficult since he would have brought up other questions I was not ready to answer. The reason I asked you to keep this a secret from Eren is because I want to tell him the origins of his powers myself when he is ready to know. Right now, I feel it is still too soon and I still do not have all the answers to the questions I know he will ask. I don't know if I ever will but I want to be as ready as possible when the time is right. Do you understand, Mikasa?"

Mikasa nodded "Yes, I understand. You have my word, Zoe. And thank you for telling me the truth."

"You're welcome. I hope this knowledge will help you assist Eren better but you must also guard yourself as well. He may frustrate you at times but I can see that Eren does love you very much. He needs you and the world needs him; if something were to happen to you, I don't think Eren would have the will to keep fighting and humanity may very well be doomed."

Mikasa felt her face growing hot at the professor's words but knew Hanji was right. So much depended on Eren and not only did he needed to be physically protected at all costs, his morale and spirits also needed to be kept alive as well, a responsibility that is now solely hers since most of their friends and comrades were gone.

"Yes, I will take your words to heart. Thank you for everything you've done for Eren… and for me. It's getting late and I must be heading back before the others notice I am gone. I trust you will be ok watching Eren by yourself?"

"Of course. You have my word I will not leave his side until he is fully recovered, just like before. Just focus on taking care of yourself for now and leave Eren to me. We may have won this day but the war is still far from over. Both of you need to be strong for what lies ahead."

"I understand, Zoe. Have a good night and I will see you tomorrow."

"You too, Mikasa. Good night."

A/N: Ok, this is the fourth drabble and it is a story mostly for Hanji and Mikasa. And while I know there is really no evidence in the anime that Hanji actually knows the Jaegers, I thought it would make for an interesting story that could be canon and I hope my readers enjoy it! I also thought it best for Eren not to be awake to hear what his father did to him, especially after having his limbs severed: p See you next chapter! ;)