Irina wasn't sure when it began, but if she had to say it would be when she was ten and Katerina was fourteen.

The age didn't really have anything to do with the problem Irina was going through, although she did blame the hormones her sister had and the whole emotional confusion puberty was making her sister go through.

But, by that logic, she should blame her sister's ignorance to reality. She should blame her sister for being a romantic. She should Katerina for believing in love and letting it control her.

However Irina found that she could never blame her dear big sister, she could never stay mad at Katerina for long after all. Just like Katerina had a list of men at the palm of her hand, she had Irina as well.

Irina didn't mind. Because no matter what Katerina was her sister, even though Katerina could be an idiot sometimes.

Such as now.

"It's love, Irina." Katerina dreamily sighed, a warm smile on her features.

Irina was almost jealous. Almost. That smile didn't belong to any of the males in their village, that smile belonged to only her and mama.

Instead the blue eyed brunette sighed and stared at the burning candle. "Are you sure it's not just the hormones?"

"Yes, I am."

"You sure?" Irina repeated, her eyebrows knitting in concern.

"I love him Irina. He makes me happy."

Irina scowled. "He's sixteen. Sixteen." The younger Petrova repeated. "And you're only fourteen Kat. You don't know what love is yet." It was only when the words escaped her mouth that Irina realized she may have hurt Katerina's feelings.

"What do you know about it?"

Irina winced, practically feeling the hurt Katerina felt, and turned around to face her big sister's hurt look. "I'm sorry. I shouldn't have said that. It's just...I want you to be happy, the way you deserve to be."

"But don't you think he can do that?"

"He won't even introduce you to his parents Kat. Nothing good ever comes from a secret relationship."

"He's waiting until I am of age to propose." Katerina quietly said.

Irina sighed. It was typical of Katerina to let her feelings cloud her judgement, and if Irina had a say she won't let Katerina's jealousy towards Elena ruin things this time around.

"Just don't tell father, alright?"

Irina closed her eyes. "Like I've ever told him any of your secrets before." She quietly scoffed.

She didn't need to open her eyes to see Katerina smiling at her. She could practically feel that smile from a mile away. Because that's the smile she wanted to protect.

And she'd go against witches, Originals and even Klaus to protect it. A brief part of her wondered if Katerina would have done the same for her.

"I do love him, you know?" Katerina quietly asked.

"Yes, doesn't mean I like him though."

After that their relationship became more strained.

Katerina would often sneak out or do things without their father's knowledge and Irina would always cover up for Katerina despite disapproving.

But that wasn't what hurt Irina most. The fact that Katerina gradually started spending less and less time with her was what made Irina hurt and sad.

And even though their mama would try to help, Katerina was too fooled by her delusion of love to realize she had begun neglecting her dear sister.

In turn Irina stopped sleeping in the same bed as Katerina, a ploy which she hoped would gain her sister's attention again.

But it didn't.

Katerina didn't even seem to notice that Irina wasn't sleeping with her anymore.

"Give it time. Katerina's just going through a phase." Her mama gently told her.

"It's been over a year mama!" Irina snapped harshly. Realizing she had let out her anger on her mama her lips tugged down into a sorrowful look. "I'm sorry mama."

Her mama only gave her a gentle and understanding smile.

"I hate her." Irina bitterly said as she stared at the empty chair where her sister should be. Where Katerina should be smiling at her.

"Where's Katerina?" Her father asked making her startle in surprise.

She glanced at her father and then back at the empty chair. "She went out to get water."

Irina didn't dare to break eye contact with her father, only breathing out in relief once her father left their cottage.

"See? You love her. Otherwise you wouldn't have lied about her whereabouts."

Sometimes Irina wondered if her mama knew more than she let on.

"I still hate that she doesn't know I exist anymore."

"My little Moon," Her mama cooed gently. "It is only human to expect that the person who has stuck around for so long would not leave you. We tend to think that what we have will never leave."

Irina pouted. "I've never forgotten about her."

"You've never been in love."

Irina turned her wide eyes to her mother. "You know...?"

"She may fool your father with her act, but I can see it. It's in her eyes."

"I just fear he is using her." Irina softly sighed before standing up. "Looks like I have to go get water. Katerina owes me...again." Honestly, she's lost count on how many times she's done these favors for Katerina.

"When the stars disappear, she'll realize that the moon has been there all along, my little Moon." She heard her mama say before she left.

It managed to make her smile a genuine smile.

Being Katerina's moon was basically her role in life right now. Even if Katerina herself didn't know that.

Irina whistled a cheery tune as she skimmed through her notebook detailing the events of The Vampire Diaries.

It was all written in English, but she was sure she would have to learn another language or come up with a code to hide the content.

Just when she was about to blow out her candle to sleep, she heard it. The sound she hated the most.

She heard Katerina quietly sobbing.

Without even a thought she bounded over to their room, yes theirs because even if she didn't sleep there anymore it still belonged to the Petrova sisters, and found her big sister trying to muffle her sobs with a pillow.

"Katerina." Irina calmly said joining her sister on the bed. "Kat." She muttered weaving her fingers through her sister's dark brown hair.

The next second she was brought into a bone crushing embrace by her big sister.

"Y-you w-were right!" Katerina hiccuped.

Irina's eyebrows furrowed. "What happened?" She asked.

"H-he forced me to...and then..."

Irina's blood went cold. "He stole your virtue by force." Irina said it in a statement.

Katerina nodded, tears still streaming down her face. "I-I'm going to become pregnant...a-aren't I?"

Irina hated to be the bearer of bad news, but she nodded anyways. "Yes." She didn't mean to sound so harsh, but if Katerina had just listened.

"Father..." She trailed off.

Irina's grip on her tightened protectively. "I'll make sure he doesn't lay a hand on you Kat."

"Why?"

Irina blinked in confusion. "Huh?"

"Why are you helping me?"

Irina's face softened at her sister. "I'm your little sister Katerina. I will always be on your side. Always and forever."

Katerina only looked guilty and Irina sighed. "Sleep, we shall deal with father tomorrow." She cut off whatever apology Katerina was going to make.