Author's Note: As soon as I wrote my first Doctor Who-fic the idea for this sequel popped into my head. This is an alternate ending to the Tenth Doctor's regeneration in "The End of Time", but written in the universe I created in "Down a dark path". You can read this as a stand-alone story, but it makes a bit more sense if you've at least read my first "Down a dark path"-fic (the companion piece is optional). I can't really tell you much more about what's gonna happen here without spoiling it. So, without further ado, I give you: "Down a dark path: His own worst enemy".

Regeneration

The journey past all his former companions and friends has exhausted him, but the Doctor is determined to make it back to the TARDIS. Sharp pains shoot through his body, making him groan in pain. Only a nearby wall prevents him from falling face-first into the snow. I have to hold on, I don't… I don't want to go. Not here. Not like this. He staggers out of the shadow into the area beneath one of the lights, one hand on the wall as he tries to cross the square to get to his trusted blue box.

As the world whirls around him he sobs quietly while the pains that ravage his body grow stronger by the second. Finally he collapses to the ground, his eyes clenched shut in agony. I can't make it, I can't… I just can't. Just then a song becomes audible and he looks up to see Ood Sigma standing in the snow.

"We will sing to you, Doctor. The Universe will sing you to your sleep."

The Doctor looks up at Ood Sigma, who replaces his translator ball, and the Ood song becomes even clearer. I can't give up, I have to make it to the TARDIS one last time. He struggles back to his feet as the song somehow grants him strength. With visible effort, as the Ood back in the Elder's cave raise their hands and the song reaches its end, he staggers onwards to the TARDIS.

"This song is ending, but the story never ends."

His teeth clenched, the Doctor manages to get to the door of the TARDIS and unlocks it, stepping inside and leaning against the door as it closes behind him. He gets up the ramp, supporting himself on the rails, and removes his duster, throwing it over a beam before looking at his right hand. It is glowing with the energy of regeneration. I can't… I can't hold it back any longer.

He looks at it almost in wonder, his eyes filling with tears, before moving around while holding on to the console. For the last time he sends the TARDIS off, staring up at the central core. Now the Doctor, that brilliant man who saved the universe countless times over, looks like a lost child as he walks around the console. I don't want to go, I don't… Is this my reward? Is this what I get for giving my life? For losing my loved ones? For saving the universe? Instead of life all I get is death. It's not fair! I don't want to go! Fearful, with tears welling up in his eyes, he voices that last thought.

"I don't wanna go."

The regenerative energy intensifies, burning the Doctor's face as he fights for breath. As it increases in strength he begins to cry before finally throwing his head back as the process of regeneration takes full effect. Out of nowhere a hand grabs his left wrist. The swirling energies halt without so much as a sound. The whole universe comes to a full stop.

"And what if I told you that you don't have to go, hm?"

The voice is familiar, even though there's a disturbingly dark and frightening edge to it . Too familiar, in fact. A shiver runs down the Doctor's spine as he turns his head to look at who's standing beside him in the TARDIS. No. Nononononono, it can't be. It just can't!

"You. You can't be here, not now! It's in direct violation of the-"

"-Laws of Time, yeahyeahyeah, been there, done that, threw them all out the TARDIS so to speak. I'm offering you a chance at life, Doctor. I can stop this regeneration, I can make you stay like this for a little while longer. How's that for a reward, hm? How's that for a big thank-you-very-much-for-saving-our-asses? Wouldn't that be fair, Doctor? Wouldn't that be just? Wouldn't that be what both of us deserve?"

The Doctor's been face to face with some of his former selves, but this… This is an abomination! How… I don't remember doing this. I don't even remember looking like that! The Doctor feels like he's staring into a mirror. A mirror with just one flaw. The other's eyes have completely black irises instead of brown. However, everything else is disturbingly the same. The suit, the hair, the grin, the way he talks, the way he moves. He's ME! But how? How is that possible?

"I see your brain's working overtime, dear Doctor. Or should I say: Dear ME? How can I be here? You don't remember doing this, you'd never interfere like this, never break the First Law. So, how is this possible? And what on Gallifrey is wrong with my eyes? This is all one big conundrum, isn't it? That alone should be sufficient to take me up on my offer, I'd think."

"But, how, I mean, I can't… The First Law! I know I've done it in the past, but never like this. Never while I still looked like, well, me! This is, this is unprecedented. You, I mean, I, I mean, we, we can't do this. It is forbidden. The universe won't stand for this!"

The face of his other self contorts in anger after hearing what the original Doctor has to say. The rage that eminates from this other version of himself makes the Doctor want to recoil, but he's unable to do anything other than talk or move his head. By some unknown means his dark-eyed self has frozen this moment in time. The Doctor is powerless. All I have now are my words.

"It is forbidden? The universe won't STAND for this? The universe is a mess, Doctor. All of the universes are a complete and utter mess. And all you, me, we've been doing is cleaning up after someone else. All we ever amounted to was running to try and catch up and fail miserably. You, me, all of us, we're a JOKE! We're nothing more than the universe's cleaning lady, summoned after the deed is done, the crime has been committed, after, well, after stuff has been broken! And don't you dare, don't you DARE tell me that it was worth it! Don't you dare tell me all those lives, all those people I knew and loved and cared for and who I all lost in the end, that is was WORTH it! They took them from us, Doctor, they took our family, they took our friends and then, when I thought I had a chance, a shot, at feeling something I thought I'd lost all those years back, one man, one spiteful, blind, stupid, hatefilled man took her away from me."

His other self sighes and for a moment, the outrage, the despair, the hate seem to leave him. Who's he talking about? He's not… He can't be talking about Donna or Martha. Or… Or Rose. They're all safe, I made sure of that. So who's…. The Doctor's eyes widen. Oooh. He's talking about… About Jenny?

"You're talking about Jenny, aren't you? Aah, I see. You're talking about our time on Messaline, when Cobb shot her. That's what you mean! But, but how, how did that change you? I didn't change. Well, not by a lot, it hurt for a while, oh yes, but my eyes didn't turn black and I didn't visit myself at the end of… At this regeneration. So, what happened? What made you come here, like this, and how can you offer me, well, what you've just offered?"

To the Doctor's delight his other self looks shocked, but then that alternate version of him regains his composure and grins.

"Oh, you are smart. Clever, clever Doctor. Of course you would figure it out, but this fast? I should've anticipated that. After all, we're the same, you and I."

The other Doctor's grin widens.

"But you know what? I'm not gonna give you the details. It's kinda personal. Yep. No need to go into that. So. Whaddaya think? Whaddaya say, old buddy, old pal, old me? Want to give it another go? Save the universe once more? Live the life you feel you've deserved? I can do it, you know. I can heal you and preserve you at the same time. That is… If you let me."

The Doctor doesn't trust his other self. Not for one second. He reminds me of the Valeyard and my seventh self. Dark. Manipulative. Only looking after his own interests. The memory of the Valeyard still unsettles him. To this day he still doesn't know if that other self is fixed in time or not. Oh, I do hope it's not. But he, me… What's his angle? What does he gain by giving this to me? Is it… Would it be worth it? To stay me? To, to actually cheat death? For this once? Would it be so horrible for me to say yes?

One look into the other's eyes is enough. Oh yes. He's even more dangerous than I thought. I don't know what happened to him, but he's an abomination. The timestrands around him behave erratically. It's as if…

"NO! You are more than an abomination, you are… You are a Living Paradox! That is… Ooh, that is so wrong, so utterly wrong. You are not me, you never were, never will be, I'll see to that! Whatever it is you want from me, I won't give it to you. Never! You are… You are all that I swore to eliminate when I time-locked the Time War, when I destroyed Gallifrey. Your arrogance, your utter hubris… It stops here. Leave me. Leave me to my death. I don't want to go, oh no, I still don't want to go. But I'll be damned before I help you get whatever it is you want from me. Now LEAVE!"

The force of the Doctor's voice makes his other self take a step back, which makes the Doctor smile. But his smile disappears as he sees the grin of his other self change into a snarl. The hand that's still around the Doctor's wrist tightens its grip. His other self leans in closer and whispers into his ear, his voice dangerously low.

"You… You don't know what you're turning down. You sad, pathetic, horribly small-minded excuse for a Time Lord. You're not even worthy to bear the name of that great and magnificent race. I am a true Time Lord, the Time Lord Victorious, the Oncoming Storm, the Bringer of Darkness. I am all that and more. And no one, least of all you, is going to stop me. I never give people a choice, not anymore, but I gave you a choice, just for old time's sake and because you're me. You refused, so you're resposible for what happens next. Now… Give it to me!"

Pain. Horrible, excruciating pain shoots through every fibre of his being. The Doctor has to pour every ounce of effort he has into staying conscious. What… What is he doing? His other self laughs maniacally while the Doctor feels the regeneration energy being absorbed back into his body, then streaming out of him again through the hand of his other self. He's… He's absorbing the energy. He's… Ooh, this hurts so much! He's killing me! The pain intensifies, sears his nerves, burns his skin. I can't… hold on… much longer…

It stops. The pain is gone completely. The Doctor drops to his knees out of sheer exhaustion. When he looks up, his other self emanates the familiar afterglow of regeneration. He looks at his own hands. Nothing. Not a trace. He turns them around again and again, feels his face. Nothing. No residual energy. Wait… Wait! He looks closer, touches his hair, his face, his nose. I'm me. I'm still me! Oh YES! Again he looks up. His other self smiles, but the smile doesn't reach his eyes. The happy feeling the Doctor has about him still being himself evaporates instantly. Evil. Yep. I'm definitely evil. Or he is, at any rate. But what has he done to me?

"Oh, lighten up, Doctor. Why so serious? I've given you your life back. That's all I ever wanted to do. As for me, well… Remember all those times you fought the Master? How he seemed to keep coming back over and over and over again? Just like most of your other enemies? They kept on coming, threatening you, threatening your loved ones, harassing, talking, nagging, tugging, whining, begging, oh yes, sometimes even begging, until you had enough. You made sure they never came back, didn't you? You act as if you're all high and mighty, but in the end, you are like me. You just don't know it yet. And guess what? Thanks to you, I will be the one who keeps on coming back over and over and over again until I have what I want. What I need. Thanks to you, I can start over. I have reset time, if you will. Now, you're still weak from what I just did, so don't even bother to try and get up and do something Doctor-ish. I'll be out of your hair in a few seconds anyway. So… Enjoy your life while it lasts. I know I will."

A swirl of green light envelops the other Doctor and he's gone. What in the world was he ranting on about? Reset time? And how did he get off the TARDIS? I've never seen a teleportfield emit green light. And what about… He shakes his head. No matter, let's get up first. Slowly but surely the Doctor stands up, grasping the console and inadvertently pushing buttons and triggering handles. The TARDIS responds with a soft humming noise, as if she's urging him on and letting him know she's ready to do whatever he needs her to do.

Finally he's able to get up. He stands like that for a while, two hands on the console, waiting for the dizzy feeling to dissipate. He checks his pocket to see if his faithful sonic screwdriver is still there. Yep. Well, that's everything accounted for. Still have my body, still have my TARDIS, still have my screwdriver. The only thing that's missing is… His hearts ache as the memories of his three recent companions surface uncontrollable. He sees their faces. Donna Noble, Martha Jones, Rose... Who can I turn to? Donna's memory is wiped clean, Martha has her own life and Rose… Rose is gone. Lost to me forever. Another face surfaces. Jack. Torchwood. Jack. Am I that desperate? He ponders about it for a few seconds. Oh yes, I'm definitely that desperate. At least I'll see a familiar face, have someone to talk with. Well, not talk with, but talk to in any case. Alright then!

"Besides," the Doctor says as that familiar smile appears on his face again, "I've been talking to myself too often, haven't I, you old chunk of machinery? Let's go then. Allons-y!"