Human!Puppet X Reader - Jealous Little Angel

You visited Jack almost every day. It's really fun to hang out with him even though you always need to take your little sister [Sister's Name] with you.
It's not a problem since she's very well-behaved and she can spend the time playing the games inside the Pizzeria while you're able to meet up with Jack.
But lately, [Sister's Name] is feeling a little bit dissatisfied. Why? Because her beloved big sister is not around to watch over her most of the times.
The thing is, she's quite attached to you and doesn't like people (especially boys) who takes her big sister away from her. [Sister's Name] can get pretty overprotective for somebody that young.
Inside and outside the nursery school, she's considered a "little angel" because of her sweet, caring personality and good manners. Even if she gets angry, she mostly makes a pouty face and still manage to look cute.

Today [Sister's Name] got a plan. She will secretly follow you to the room you're always hanging out and possibly able to see who you meet up with.
She watches you from the corner of her eyes as you walk away and that signalized her to follow you right now. She followed you with silent steps to the room which turns out to be the Prize Corner.

"Isn't that the Prize Corner?", thought [Sisters's Name] and instantly brighten up. Maybe you're just here to get her a prize? But her smile dropped at the sight of an unknown boy.
Who is that boy? Only a stranger or possibly your boyfriend? [Sister's Name] widened her eyes when you kissed the boy on the cheek. "Well, definitely her boyfriend...", she thought and pouted.

You and Jack started dating not long ago. Your relationship with Jack is like a fluffy romance: Holding hands, sharing sweet kisses and so on. It definitely won't be long till you two take the next step.

[Sister's Name] had seen enough. She stormed into the room directly towards Jack, rapidly throwing small punches at him and yelled: "MY BIG SISTER! YOU CAN'T GET HER!"

You stared at her in shock. "[Sister's Name]?! What are you doing here?!" Jack picked your sister up like a kitten and asked: "Let me guess: Your younger sister, (Y/N)?"

"YES I AM HER YOUNGER SISTER! LET GO OF ME!" [Sister's Name] flailed around wildly and you facepalmed. "Jack. Put her down please." Jack let her go and you squat down to her eye level.

"Care to explain, [Sister's Name]?" Her eyes watered and she hugged you. "It's just... Everytime we visit the Pizzeria, you're not around to watch over me... It made me suspicious so I followed you..."

You feel bad right away. You hugged her back and said: "I'm sorry... I'm such a selfish person. I don't deserve to be the older sister of a cute little angel like you... Can you forgive me?"

[Sister's Name] smiled brightly and said: "Of course I forgive you! How can I not? You're the best big sister I can ever have!" Then she pointed at Jack.

"You there! It seems that my big sister likes you very much but I can't accept it yet! You must prove that you're worthy of her love! I challenge you to a game of chess!"

Jack grinned and bowed. "I accept your challenge."

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"WHAT?! How did I lose to a little girl?!" [Sister's Name] giggled and clapped happily. "I didn't know that it would be so fun playing with you! No wonder that my big sister likes you! But..."

[Sister's Name's] expression changed to a serious one. "I can only accept your love for her if you're able to beat me! Another round?"

Jack growled and set his poker face. "Hell YES! I'm not giving up! You'll see! I'm going to win this time!"

You sweatdropped. It looks like Jack found himself a rival.