Original Theory/Prompt

Kara didn't imagine it would go the way it went. The way Lena stared at her. The silence that filled the apartment. The chill that went down her spine. The emptiness of her eyes.
The deeper they get into it, the more terrible things get. Because their friends Oliver Queen, Barry Allen, and Kate Kane come from Earth-1, requiring their help because of an impending crisis.
The longer it goes on, the more tension there is. Yet the more that happens, the less confusion there is eventually.
Someone's going to have to make the ultimate sacrifice. But if it's one of the two destined lovers, then what will one do without the other?