Overprotective: AOT/KNB Crossover [Reader x Eren]

Side Story: Himuro's Life

~before Himuro met (y/n)~

~from Narrator's POV~
She wasn't particularly fond of him. They were related, yes, and he was her sole heir, but blood wasn't necessarily thicker than water. Their relationship had always been tense; she simply wasn't made of "mother" material. She was a woman, and a firm one at that, but any maternal side she was supposed to have seemed fairly invisible to Himuro.
When she became too annoyed by his presence, she sent him overseas to America.
He was eleven at the time.
He made a few friends by picking up basketball, but he didn't feel like he truly belonged in America any more than he did in Japan with a mother who couldn't stand his presence.
The longer he was separated from his mother, the more he realized his disgust for her. Parents had a responsibility, didn't they? They weren't supposed to just ship their kids off when they needed to focus on their work. They were supposed to teach their kids how to ride bikes and tie their shoes and...
Himuro drove his fist into the wall beside the phone. Then, taking a deep breath, he dialed the only number he knew by heart, waited for it to go to the answering machine, and gave his weekly report to his mother that all was well and that he was still maintaining his grades and eating well. Then he hung up, his heart feeling cold...
He sank to the floor.
What's my purpose? What's the point in any of this - in keeping up my grades, in learning basketball, in living? I'm living for myself, but nobody is living for me...I can't find anything to fill this void inside of me...
He realized that tears were rolling down his cheeks, but he didn't bother wiping them away. What's the point? I'm crying on the inside anyway...
***
Two weeks later, he left America and returned to Japan, feeling more hollow than when he'd left.
From that point on, he felt even more distanced from his mother, and he kept himself separated from her, disgusted by her very nature. When she started bringing home a man, Himuro avoided him, too, furious.
I hate him...I hate her...I hate EVERYONE. Why can't they all just go away?!
When Himuro heard his mother's lover speaking of a daughter, he was quite honestly surprised, leaning back against his door from where he'd been eavesdropping. He has a daughter? He has to know that taking on a lover hurts his child. I mean, my mother's lack of attention hurts me...Not that I want her to pay attention to me...
At first, he felt a strange kinship with the daughter of the man his mother spent her time with - for he didn't know if she could "love" anyone. But as time passed and Himuro remained alone, he began to resent the daughter.
What if my mother cares for that man's daughter more than she's ever cared for me?
That's not the way it happened, of course, but Himuro couldn't get the thought out of his mind...
If my own mother chooses a different child over her own blood, then I will have no worth...If my own mother doesn't love me, who ever will?
With poisonous thoughts swirling in his mind, Himuro slowly got up, pacing in his room. He couldn't confront his mother...but this "daughter" was a different story...
***
The next morning, with both of their parents gone on a weekend trip, he left the house and walked to the house he'd seen his mother stop by on multiple occasions. He glared at the door, hating that it represented the family his mother preferred over him. He knocked on the door, ready to unleash all of the pent-up insecurity and anger on the daughter who was taking his place...
...but when the door opened, he found his words dying in his throat.
She's just like me, he realized, his mouth slightly open.
Her wide eyes met his, and all he could think of when he saw her was a skittish cat.
Hesitating, he bent down to her level and let a smile form on his lip, the shape unfamiliar to him. "Hi. I'm Himuro..."