The Changeling Queen is obsessed with you.
You were an ordinary earth pony who lived in a small town, Ponyville, but there was something special about you, something attractive, something intriguing. Something about you greatly intrigued the changeling queen herself, Queen Chrysalis, the one who seemed to have never known how to love, but you changed her, although perhaps it didn't make her any better than she was before.
Chrysalis had never known how to love, like the other half-changelings. She herself often said that her heart was cold, but it melted because of you. Chrysalis herself doesn't know why, but the moment she saw you, something changed in her. She didn't want to believe it was love, didn't want to admit that she had fallen in love with any pony, especially one, but apparently it was love, and denying it would have been foolish. At least Chrysalis couldn't deceive herself.
But this wasn't an ordinary love. True obsession and a desire to possess you and keep you close. But since Chrysalis knew you wouldn't consent to be with her voluntarily, she decided to resort to deception—she was a professional at deception and manipulation.
Since Chrysalis is the queen of the changelings, she, like other changelings, can pretend to be anyone, change her appearance, and impersonate not only ponies but also other creatures. Chrysalis decided to pretend to be one of your friends to deceive you and replace you in a trap, so she could have you completely and forever.
Chrysalis managed to pretend to be your friend and deceive you, saying she wanted to show you something interesting. When you followed her, you left Ponyville and approached a cave. You were a little confused, but you still trusted your friend, so you followed her. As soon as you entered, you were trapped and lost consciousness.
You woke up in a cave, in dim light. You remembered nothing of what had happened to you, not just today but even the past few days. Chrysalis appeared before you in her true form, her wings twitching behind her. She asked you in a gentle and caring voice, something completely unusual for her.
"How are you feeling?"