Hooray! Plot bunnies!
As we all know, the world of fanfiction is the world we run to when something bullshit happens, like Donna having her memory wiped. Who needs the show, anyway, I'll make it up by myself if they can't manage to scrape together a bearable ending.
Although, maybe I'm just pretending that's why. Maybe I'm actually distraught because Donna is gone. Maybe I'm incredibly pissed off at the Doctor for NOT DOING IT RIGHT. "DONNA IS HAVING ISSUES; I'LL MAKE HER FORGET ME COMPLETELY, BEST PLAN EVER." Also, I'd like to take this opportunity to rant about the discrepancy: the Doctor said that Donna's family weren't EVER allowed to mention his name or the TARDIS or anything to her, but she saw him when she woke up and that didn't trigger her memory... so... answers please.
Also, typing with a broken finger is remarkably unpleasant. The finger is fine until it touches anything, so I forget not to use it and then it hurts, so I leave it, then it doesn't hurt anymore and I forget again. God damn it.
They were experiencing that brilliant moment after a huge crisis has been averted. That sheer glee of being free of obligation... like when you finish an important assignment and realise that you're actually about a tonne lighter for it.
There was just one little problem – Donna had the knowledge of a Time Lord crushed into the brain of a human. That couldn't possibly be good.
The next few minutes passed in a haze – Donna lost the ability to talk, and fainted in his arms after begging him not to make her go back. He was fighting tears himself as he lay her down gently against the console, hoping absently that she wouldn't roll about too much when he flew.
Directing the TARDIS alone again made him even sadder.
A few minutes later he was hauling her to her own front door, mind clear – he would wipe her memory of everything, everything, so that the metacrisis didn't kill her. She had wanted to travel with him forever, wanted to stay with him until she died, be it old or young. She had wanted it... and so had he – but he refused to believe that losing her memory and going back to her old life was a waste.
He just had to have a sharp word with her mother.
As he was about to cross the road to her house, he sighed through his teeth. He hadn't thought this through, had he? He couldn't just show up on the doorstep and wipe her memory in front of her family. He turned around and made his laborious way back to the TARDIS, teeth grinding unconsciously.
He lay her down – again – near the console, and was just pulling out his sonic screwdriver when he realised something – something HUGE.
What if he didn't have to wipe her memory of him completely? What if she didn't have to lose her? What if he didn't have to lose him?
What if he just wiped her mind of the past few days? What if he got rid of the evidence of the metacrisis in her mind, but didn't get rid of himself in her head?
The amazing knowledge of a Time Lord wouldn't just materialise back in her head if he erased it, that sort of vast experience couldn't just pop back into her mind, it couldn't just return after it was eradicated.
What if?
For one shining moment, he was thrilled. Everything seemed like it would be alright... and then he thought how hard it would be to navigate specifics in her mind. It was easy enough to erase a concept from a mind, like 'the Doctor' and 'the TARDIS' and 'time travel', but a whole other story to try to isolate a time frame and alter that... he could make her forget how to talk... or forget how to make her heart beat.
Was it worth the risk?
What if she died? What if her death – Donna's death, his Donna's death – was by his hand? Just like all the others? Just like the Midnight attendant, and the boy prodigy, and the rest of them?
He couldn't make that choice.
Then he remembered – if Donna had been there, she would have chosen for him, and she always chose right. He would have been dead under the Thames without her. He would have left that family to die in Pompeii without her. He would never have defeated the Daleks without her. She would die for him.
She would die for him.
But could he let that happen?
On the other hand, could he live with himself knowing he had defied the dying wishes of someone he'd be dead without?
"You know what?" he said, speaking aloud for the first time. His voice echoed from the walls of the TARDIS, making him feel suddenly lonely. "I'm going to do it."
He looked down at her face. He couldn't explain what he felt about what he saw there – she was gorgeous. She was incredibly smart, but so stupid in that she refused to accept it. She was the most important woman in all of creation.
"And you know what?" he said, aloud again. "I love her."