Elsa blushed as she remembered what she saw through the crack of their door.
As Kristoff ran his hand along her back, she let out a moan and let her hand run through his hair. She had a soft looking back, lightly dusted in freckles, creamy thighs, and red hair.
Anna.
Their lips locked, tongues dancing. Elsa felt a pang of jealousy make it's way into her heart. But, she loved the sounds Anna was making. She felt helpless to know that Kristoff had made Anna feel this way and not herself.
She watched as the two lay in bed, sheet less, bodies exposed. Kristoff was on top, Anna on bottom. He positioned himself in front of Anna's entrance. Elsa winced at the size difference. Anna was probably not even half the size Kristoff was, and his member was rather large. "Ready?" She heard him whisper, voice husky. "Yes..." Came Anna's breathy moan.
She watched as Anna tensed and her breath quickened. Kristoff stopped moving. 'Anna is a virgin?' Elsa thought. Anna let out a soft cry as Kristoff pushed through her barrier. He leaned down and wiped the tear away from her cheek. She cupped his cheeks and kissed him. "Are you alright?" The blonde asked. "Y-Yeah..." Anna replied. After a few seconds Anna nodded.
Kristoff started out slowly, trying to find a rhythm. Anna had started panting again. "F-Faster." She breathed. He obliged. Now he was thrusting, sweat beaded his skin. Anna, below him had her arms wrapped around his neck, hands twirling the hairs at the nape of his neck. His muscles rippled under his skin as he thrust into her. He thrust in hard once, and Anna cried out. "Ah!" 'This is so... Sensual, and loving.' That word made her shiver. Loving. Not her, no one but Anna even cared about her. 'Anna...'
Kristoff let out a low groan. Clearly Anna was not the only one enjoying this. Anna looked up at Kristoff, who was staring back at her. They leaned in and kissed again. Anna cried into the kiss as she came. Kristoff looked into her eyes as their tongues danced. Releasing her lips, he sped up, if that was even possible.
Anna, having just came, was even tighter and more sensitive. Kristoff was very close, and the tight squeeze wasn't helping. Her walls clenched his member as he thrust, earning a grunt. She cried out once more. "Kristoff!" "Anna!" The two came together. Kristoff slowed, the two riding out their orgasm together. When he came to a full stop, Anna smiled at him.
Anna grabbed his hand and placed it on her cheek, nuzzling it. "I love you." She whispered. He leaned down and kissed her, passionately. "I love you too..." Kristoff pulled out, and pulled Anna into an embrace. Elsa shivered as Anna's breasts were gently sandwiched as a result of their hug. Kristoff pulled the sheets over the two and whispered something into Anna's ear that made her giggle. Once the two were asleep, Elsa stumbled down the halls into her own chambers.
Climbing into bed, something hit her. 'I just saw my sister have sex with her boyfriend.'