This is the Doctors final good bye to River right after Darillium. I got the idea for this story from a comment on this video watch?v=z8Yssg1FBYg. The commenter is Caroline Brunner and she said

"We seriously need to see the Singing Towers of Derillium. I think that should be Matt's last scene. Oh God that would be beautiful, especially since we know that he could hold his regeneration back for a little while. God that would be so lovely."

So here it is :D

The TARDIS landed and she stepped out; she was back outside her the home left to her by her parents.

"Are you sure you won't stay the night?" She asked with one eyebrow cocked

"No. I can't, and besides, you have to be up early in the morning" He tried to smile.

"Early, schmearly; I'm only going on an expedition to a library"

"No, River, you're going on an expedition to the library, the biggest in the universe, and I highly doubt Mr Lux would be too pleased if you turned up less than bright eyed and bushy tailed"

"Alright" she sighed "Thank you for the picnic on Darillium, Sweetie. I do love the singing towers"-

"It was my pleasure, Doctor Song" he smiled

"And for your screwdriver; you barely let me look at it at the best of times"

"Well, I know I can trust you completely and you will take exceptional care of it"

She held his face and kissed him. He wrapped his arms tight around her waist; he knew this was their last kiss. She could feel tears running down his face onto hers so she withdrew but he was still holding her as close as he could.

"Sweetie, please tell me what the matter is?"

"It's nothing" he wiped his cheeks

"Why are you crying so much?"

"I- I"- his mind racing for an excuse "I've been thinking about the Time-War a lot; the singing towers look kind of like Gallefrey in the distance"

"Oh Sweetie" She held him "You did what anyone in your place would have done. It wasn't your fault" she stroked the back of his head "But I know that's not the reason"

He withdrew and looked her in the eye "You best get some sleep, River" there was a lump in his throat.

"I won't be able to rest without knowing you'll be alright" She held his face.

"I'll be fine, don't you worry" he forced a smile.

"My mad man with a box; all your secrets"

"And you know my biggest" He remembered meeting her in the library ("River, you know my name, you whispered my name in my ear. There is only one reason I would ever tell anyone my name, there's only one time I could")

"What do you mean?" She placed her hands on her hips

He leaned forward and whispered in her ear. She stood there frozen with shock.

"And now you know" He smiled.

She shook her head and frowned "It's not as grand as I thought it would be. I mean, everybody knows a"-

He raised his finger to her lips "Ah-ah-ah. It's a secret, remember"

"Aright" she lowered his arm before yawning

"See. I knew you needed sleep" he let out a low giggle

"Fine. Goodnight, Sweetie" She kissed him quickly and walked towards her home. He leaned against the door of his blue box and watched her go inside the house her parents left behind. She blew a final kiss before closing the door behind her.

"Good bye, River" he began to cry again as he stepped into the TARDIS. He felt weak. When he reached the centre console his emotions got the better of him. He started shouting and began pulling at the console, tearing off any stray wires or buttons and throwing them around the room.

"I have seen the birth of the universe! I have watched time run out, moment by moment until there was nothing left! No time, no space, just me! I have watched universes freeze! And creations burn! I have seen things, LOST things and know things no one should ever see or loose or know!..." He fell to his knees "I have lost so much. I can't save them. I can never save them" He held his head in his hands and sobbed "I watched her die! I watched her die and I didn't even know who she was! All we've done together. All we've seen! And I never knew!" he curled up into a ball on the floor. "I've lead her to her death like a lamb to slaughter and I don't even know it!"

The whole time he could feel it. It was burning away under his skin, he had held it off for long enough. It was going to happen "CLARA!" he called.

She came running "Oh my stars!" She was panicked "Is River gone?"

"Yes! It's time!" He staggered to his feet and WOOSH! Golden streams of light shot out from his limbs "ARGH!" It was so bright; Clara found it hard to look at him.

The Regeneration had begun