"Bash, if something happens to the Captain and Sparkles, then the Nothing won't exist any more than this place does. Sparkles was the core of the Nothing, he can't exist without the Captain and the Captain can't exist without him."

Much like how she cannot exist without Tiamat and vice versa.

"It was the entire point of him trying to kill the Captain and all of us."

From what she understood of the situation at least.

"The Captain said we would cease to exist without this place, there is no reason to think he was lying."