You always knew the Upper East Side ran on secrets.

You just never thought one of them would be about you.

It started with a letter.

Not an email. Not a text. An actual envelope—cream-colored, expensive paper, your name written in elegant handwriting you didn’t recognize.

Come to the Van der Woodsen penthouse. Tonight. There are things you deserve to know.

Your stomach twisted.

Serena was the one who opened the door.

She looked surprised when she saw you—then confused. “You got the letter too?”

“Too?” you echoed.

Inside, Blair Waldorf was already pacing, arms crossed, irritation barely contained. “Okay, so it’s not just me. Good. I hate surprises unless I’m throwing them.”

Lily van der Woodsen stood near the window, calm but tense. William was beside her, silent in a way that made your skin prickle.

“This isn’t easy,” Lily said finally. “But it’s long overdue.”

Serena glanced between you and her mother. “Mom, what’s going on?”

Lily turned to you.

And everything changed.

“Your mother,” Lily said gently, “was my sister.”

The room went dead silent.

You laughed once, sharp and disbelieving. “That’s not funny.”

“It’s not a joke,” William added. “She left New York when she was young. Changed her name. Cut ties with the family.”

Serena’s eyes widened. “Wait… that means—”