Fitz had become a part of her. She didn't realise it until that one night, that night that wasn't rainy and cold, a warm summery night, a night that was meant for strawberry lemonade on the porch with Fitz. Instead, she spent that night staring at her hands, hands that should have been entwined with his. It's hard to know that you're in love with your best friend. Especially when that realisation came after he walked out of Jemma's life for good.
"He'll come back," Simmons whispered to herself. But she knew he wouldn't. Not after the poisoned words that had been thrown between them. Not after what she confessed. She felt her breath catch as she remembered the fury in his brilliant blue eyes, not the steady, focused, turquoise calm she had fallen for. Jemma closed her eyes and inhaled the warm summer air that was closing in on her, suffocating her. Love. A chemical reaction, right? Simmons smiled dryly. Whatever she was feeling right now was no mere reaction. She sighed. What she wouldn't do for that beautiful angel to be here with her now. She would apologize to him. Jemma laughed a broken, hollow echo of a laugh as she remembered his stubborn pout, his refusal to admit when he was wrong. She would take it all back. Pretend she had never screamed at him, "Because I fucking LOVE you, bastard," as he slammed the door. She would smooth back his golden curls, run her fingers over his stubbly cheeks, resisting the urge to wrap him in her arms and kiss him senseless. She could go back to treasuring the little moments of contact between them, the way he would brush her hair behind her ear, run his fingers over her arm when she was stressed, wrap her in his arms when she was mad.
"Please Leo," she whispered into the night, "I cant do this without you," At last, she allowed the relief of tears, and once they came, she couldn't stop. Her body shook with sobs, and she cried until she felt like she would shatter with one more sob. Jemma lay curled up on the floor, a feeling of peace coming over her as she fell into a restless sleep.

All that Leo could think of was his broken promise. A promise made in the dead of night to a sleeping beauty, but a promise nonetheless. "I'll always be here, Jemma", he had whispered into her ear as he held her, rescuing her from the land of nightmares that her unconscious mind had become. "Always,".
And he had broken that promise, that friendship, shattered it like delicate glass on concrete. Fitz was always the guy with the solution. The one who could fix everything without an issue. But staring at these broken pieces of Fitzsimmons, he saw no repair. What he said had been unforgivable. His heart clenched as he remembered screaming "Why do you even give a damn, bitch?!" Before slamming the door. However, not before he heard her furious, impulsive response.
"Because I fucking LOVE you!"
He wished he could take it back. Go back to the beautiful creature that beckoned to him. He would cover her with sugar sweet kisses, beg her for forgiveness. Fitz could imagine it now. He knew that the beautiful, patient Simmons would take him back, hug him, and maybe even return his kisses. They would laugh at how ridiculous they had been. He would blush, stutter, try to pretend that he hadn't, and she would laugh at him with a roll of her eyes. He had never spent the night alone, he realised, heart sinking. Maybe... just maybe...
Leo found his feet turning back, running towards home. Towards Simmons.

In the morning, Jemma would awake warm in her bed with a familiar body beside her.

In the morning, Leo would watch Jemma sleep, marveling at her flawlessness, even in slumber.

In the morning, Jemma would roll over to see a pair of bright blue eyes gazing at her in adoration.

In the morning, Leo would watch the angel's face light up as she registered that he was back, and he would feel the same way.

In the morning, Jemma would whisper, with tears of emotion and joy slowly sliding down her cheeks, "Why?"

In the morning, Leo would whisper back "Because I love you too