The Sakamaki brothers wandered their house aimlessly. Yui had stabbed herself to save them from Cordelia, but now it appeared as though she would die and Cordelia would live regardless of her sacrifice.
They were scared of losing her, but more importantly, they were scared of what that fear meant. It meant that she wasn't just their blood bank. She wasn't just a weak human they hated. She wasn't just a source of amusement to them. She wasn't just a way to get power.
And that terrified them.
Then, Reiji came into the room and told them that his potion could save her. She was going to live, but things couldn't go back to the way that they had been. Not anymore, after they had realized how much they cared for her.
After she woke up they were all happy. For several days, Yui had to stay in bed. The brothers didn't disturb her, so that she could recover and they could learn how to deal with their revelations.
But things didn't stay peaceful for long. Because Reiji went over his potion's ingredients and made a terrible revelation.
That night, he went to Yui's room. It was the first time in his life that he wished to be wrong. But he wasn't.
When Reiji had gone over the potion's ingredients, he had realized that it was only able to temporarily repair damage to a human's heart. And since Yui had stabbed her own heart, it would only allow her to live for a short period of time.
After he confirmed this fact, he called to his brothers. Upon this discovery they were all shocked.
"Are you certain that she will die?" Shuu asked.
"Yes, her heart has already begun to develop an arrhythmia."
"If the potion healed her once, couldn't she take it again?" Kanato pleaded.
"It wouldn't matter, it can only be taken once or will turn into a poison for a human."
After the brothers absorbed this fact in silence, Subaru finally managed to choke out the question that had been going through all of their minds. "How long?"
"Maybe two or three weeks if she is lucky. A few days if she becomes too weak."
After they realized how short their time with her would be, they reached a silent agreement that they wouldn't fight in front of her, and they would allow her to choose how she lived, for the first time since they met her.