Together

Rose hardly paid any attention to Jack and others, who'd come running up to check on the Doctor and focused her attention on him.

He was growing weaker, his breathing was shallower, and he felt cold—even for a Time Lord. His eyes were mostly closed, but they opened when she touched his face.

"You-you came back," he said.

"Of course I came back. I made my choice a long time ago and I'm never going to leave you," said Rose. "This is all my fault. If only I'd gotten here sooner."

"Maybe…it's better…this way," he coughed.

"Don't talk like that," said Rose, scared now. "We're together now, everything's going to be fine, you'll see. We'll get you treated for your injury and you'll be okay soon, or you'll just regenerate or something. You'll be okay."

"Rose, I can't…regenerate. There was something…in the dagger…I can't regenerate. I'm not…going to make it."

Rose felt the tears flowing as she held the Doctor's hand to her cheek. "I'm right here."

Rose:
We are home
We are where we shall be forever
Trust in me for you know I won't
Run away
From today this is all that I need
And all that I need to say
Don't you know how you've changed me?
Strange how I finally see
I found home
You're my home
Stay with me

"You won't be alone, Doctor. I promise."

Rose…I was…never alone…" he whispered. "I've…got you. At-at least I got to see you…once last time."

The Doctor's eyes then closed and his hand fell to the ground.

"No," Rose sobbed. "Please, please don't leave me." She cried into his chest. "I love you," she whispered.

The watch ceased ticking and fell onto the table. Sarah-Jane and the others exchanged a few tears. The spell would never be broken now and not only that, but they had lost their closest and dearest friend.

Rose continued to cry into the Doctor's body but stepped back when beams of silver light swooshed down around the two of them. Rose saw the Doctor's injury heal and felt herself being changed into something else. When she felt the beat of two hearts within her chest, she suddenly realized what she was—a Time Lady. The TARDIS spoke to her.

You broke the spell. You truly love the Doctor. Because of this, neither of you will regenerate, instead you shall live a very, very, very long life together. Neither of you will ever be alone. You'll always feel your loves ones beside you, no matter what.

Rose couldn't believe it and cast her attention back at the Doctor, who was stirring and slowly getting up. He looked at himself in shock and then turned to face Rose, sensing her new form.

"Rose, I'm—you're a—"

"Yeah, I am," said Rose, grinning and wrapping her arms around his neck.

The Doctor smiled and ran his fingers through her hair before pulling her in for a sweet kiss that she returned.

Fireworks exploded all around the castle and the sky lit up with the sunshine and a beautiful clear sky. The castle was restored to the height of its glory and the others began to turn back into themselves.

"Jack!" said the Doctor, as Jack turned back into himself. "Rickey! Martha! Sarah! Gwen! Look at us!"

"Mum, mum!" said Luke, before he turned back into a kid and K-9 was turned in an even better model than before.

"Oh, my heavens," said Sarah-Jane, laughing.

"This is a miracle!" said Mickey.

Rose was swept into the Doctor's arms as he spun her around and pulled her in for another kiss.