The heart can carry memories. With memories, obsession will naturally arise. Your obsession is my obsession.
A change of heart allows one person to bear the lives of two people
"He's mine, not yours!"
"You and I are the same person now, is there any difference?"
"Are you worthy of him?"
"How could I betray him without you?!"
Step by step towards death, step by step towards destruction. Do you think this is the end?
"We are one, and you will help us get rid of our obsessions, right?"