Beautifully Broken
By Pixie Child
So she closes her eyes, and imagines that she had showed up just in time with a doctor who was able to fix her, make it so she didn't die. She pretends that they had their first kiss at a dance they didn't want to go to, but Buffy made them. When she does that, she always imagines that Cassie would taste like the bubblegum lip stuff Dawn saw in her bag the one time and that whenever one of them was sad, all the other had to do was hold her tightly until all the tears went away.
But it's just a story and Dawn knows this because instead of beside her in the caf, Cassie is in a wooden box, being lowered into the ground.