Author's Note: I have rewritten this story extensively after a reviewer pointed out I was describing Martha's actions rather than showing her thoughts and feelings. I hope you enjoy this version, it has quite a different ending than before and I feel much better about it.

After writing my first 'what-if' fic named "Down a dark path", with an alternate ending to "The Doctor's Daughter", I immediately started thinking about how the Doctor's companions would react to the decision he makes in the end. This story shows Martha's thoughts and reactions to what 'my Doctor' says and does. I've also published three parts of a sequel ("Down a dark path: His own worst enemy") already, in which we see how this relatively small change in the Doctor's life eventually influences his future. When you enjoy this story, don't hesitate to let me know or go read some of my other Doctor Who-stories. Enjoy!

Down a dark path: Martha Jones

As the terraforming gases swirl above their heads, Martha, the Doctor, Donna, Jenny, the Hath and the humans look up in awe. Both parties have laid down their weapons. Everyone watches the spectacle, everyone but General Cobb. Cobb grimaces as he looks at the Doctor. He destroyed it. He destroyed everything! Hatred makes him bring up his gun and point it at the head of the smiling Time Lord. I will not stand for this! He fires.

Martha sees Cobb aim the gun. She looks at the Doctor, but he's oblivious to the danger. Just as she wants to move, wants to shout out a warning, Jenny moves between the Doctor and Cobb. Jenny, oh God, NO! No one hears Martha's silent plea, but they do hear Jenny's shout of defiance.

"NO!"

The bullet hits Jenny square in the chest. She collapses into the Doctor's arms. Oh no, nononono, not this, not Jenny, not now, oh Doctor... She clasps a hand over her mouth and stares at the tragedy that unfurls before her. No, she can't die, not now, please, God, please, don't let this happen, don't let him lose her! Comprehension starts to seep through the mask of incredulity on the Doctor's face. Martha sees how his face changes as his brilliant mind figures out what just happened.

"Jenny? Jenny! Talk to me, Jenny!"

Panic. She can hear it in the Doctor's voice. Panic, but not the panic she's come to know over their travels together. That was... good panic. Panic that made him think faster, react faster, that made him come up with a plan to save people. But this... It scares her. True, naked panic, human in its enormity.

As the Doctor sits down carefully and takes Jenny into his lap, Martha moves forward. She bends down to check Jenny's pulse. Hm. Both heartbeats irregular, but that's to be expected after experiencing such a shock. Let's look at the- The moment Martha lays eyes on the wound, she knows. She doesn't even have to double-check, doesn't have to take a closer look. Jenny's wound is lethal. No, no, no, NO! It's not fair! She can't die, she can't! It will break him, it'll break his hearts, but I can't save her! I can't save her... Oh God, how am I gonna tell him? How, how can I say the one thing he doesn't want to hear?

"Is she gonna be alright?"

Donna! Martha hadn't even noticed Donna walking up to the three of them. And now she's asked the one question Martha doesn't want to answer. But I have to. I have to. She looks up and meets the Doctor's gaze. His eyes plead with her to not answer the question, to not make it real. But you know already, don't you, Doctor? You know what I'm gonna say. And I wish to God I didn't. I'm so sorry, I'm just... I'm sorry. Ever so slighty Martha shakes her head. She cringes when she sees tears forming in the Doctor's eyes. Right that moment Jenny speaks while she looks up at the terraforming gases.

"A new world. It's beautiful."

"Jenny? Be strong, now. You need to hold on, d'you hear me? We've got things to do, you and me. Hey? Hey? We can go anywhere. Everywhere. You choose."

Jenny smiles. She knows too. She knows he's just trying to comfort her. I, I can't- Martha tries to hold back the tears so father and daughter can share those last few moments in peace. This isn't about me. They, they deserve... Oh screw this! They deserve to be together! To see the universe! He deserves, he deserves to get to know her, to love her, to scold her, to get scared for her, he just, he just needs her to be with him! It's not FAIR! He's lost so much, so much already, and now THIS? How much more can a Time Lord take? How much more can HE take?

"That sounds good."

"You're my daughter and we've only just got started. You're gonna be great. You're gonna be more than great. You're gonna be amazing! You hear me? Jenny?"

Jenny's death is peaceful. She just closes her eyes and dies without any fuss. The Doctor's face contorts with despair as he holds her tight and kisses her forehead. Martha sees the tears glisten on his cheeks. Oh Jenny, oh Doctor... She cries for both them in silence and watches him cradle and hug his lost daughter.

Suddenly the Doctor looks up at Martha as if he just remembered something. His face lights up when he voices his thoughts.

"Two hearts. Two hearts, she's like me. If we wait... If we just wait..."

For a second Martha's sure he's right. She has two hearts. She's Time Lord, like he is! Surely that could mean...? But the body lies still. There's no sign of a regenerative glow, no spontaneous healing of the wound, no indication that Jenny will miraculously return from the dead. No. She should've started regenerating already. She's dead. She's really dead. When she opens her mouth to answer his unspoken question she sees that, like before, he already knows the answer. Why, why do you make me say it, Doctor? Why? Does that make it more real? To hear the pain in someone else's voice? To hear the pain in mine? Is that why- Martha stops before she finishes that sentence. Let's not go there again. Now it's me who's not being fair.

"There's no sign, Doctor. There is no regeneration. She's like you, but... Maybe not enough."

Her words hang between them for what feels like an eternity. Just when Marths wants to say something, she sees a change come over the Doctor. His eyes darken. The despair disappears from his face and is replaced with something she's never seen before. Something cold. Something frightening. Doctor? When he speaks, his voice sounds both familiar and chilling at the same time. Doctor, no!

"No. Too much. That's the truth of it. She was too much… Like me."

Martha knows that voice. It's the Time Lord who's speaking now, that utterly alien side of him that's capable of unimaginable and inhuman acts of wrath. Doctor, please, no, don't, don't do this, it's not you, please, snap out of it. Come on, you've done it before, snap out of it, he's not worth it, come back! But as much as she tries, Martha can't speak up, not even when she sees what happens next. The Doctor places a gentle kiss on Jenny's forehead before putting her to the ground. The next second he gets up, walks over to Cobb, who's being held by the human soldiers, and picks up Cobb's discarded gun. To her horror he points the gun at Cobb's head. She hears his strained breathing, sees the barely constrained fury that simmers beneath the surface. Oh God NO! Don't, don't do it, Doctor! Not you, not like this, not with a gun! Her mouth moves, but it's like someone has stolen her voice. Don't give in, please, don't do it, let him go, let him live, give him a choice! You always do that, you always try to save them! Even when, even when...

"Even when they're not worth saving," she whispers.

No one hears her. Tears cloud her eyes. You always try to save them, Doctor. You always give them a way out. Even when they should die. Even when they should pay for their crimes. You grant mercy. It's what you do. It's what makes you the Doctor. Please, just- A voice cuts through her thoughts. A voice that sounds colder by the minute.

"You killed her. You killed her in cold blood! You wanted to kill me, because I helped you. Helped you! Blind, arrogant, selfish idiots! All of you. Why did I ever think I could change that? Why did I ever feel I could change you by being an example? What did I get out of it? Nothing! Nothing but the knowledge that I will lose everything every time and there's no amount of time travel or mercy to remedy that!"

Every time the Doctor uses the word 'you' Martha flinches. The despair, the anger and above all the utter loneliness that resonates in that one word is almost too much to bear. Only then does she realize the full extent of the Doctor's frantic searches for new companions, how much he needed and needs and will need them. We balance him. We keep him grounded, we make sure that he stops before it's too late, that he let's go. To remind him that we all have choices. She remembers the times that she indeed had to stop him, to help him see there were other solutions. To remember his compassion. But I've never seen him like this cold, this calculating, this accusing. It's like, like... It's like he's talking to all of us. To the whole of humanity. Like he's, he's lost hope. Her own questions pop into her head again. How much more can a Time Lord take? How much more can HE take? Through her tears she sees the Doctor grips the gun tighter and hears him continue his monologue. And in that instant Martha realizes that she's about to get her answers.

"I showed mercy. I had compassion. I gave you a choice. And not once, not ONCE did I get a thank you or a show of appreciation. Not once! Ungrateful, that's what you are. All of you! All I have to show for it is a TARDIS with a broken cameleon circuit and a string of companions I've known and lost. And now you've taken my daughter. My daughter! Took her from me before I even got to know her, to show her the universe, to... To hold her, see her grow up, like I could never see..."

I'm sorry, Martha says silently, I'm so sorry! You must hate us, you must hate us to bad right now. And I can't, I can't blame you for that. After all, did we ever thank you? Did we ever acknowledge all you've done for us? Did anyone? All you ever got was loss. Loss of life. Loss of friends. Loss of your whole race. And now, now you've lost your daughter. Can I blame you for hating Cobb? Do I even have the right to judge you if you decide to kill your daughter's killer? She looks at the ground, hoping for an answer. I can't. I can't help you. I can't save you. It's up to you. And I hope you make the right decision. She hears him continue.

"I could never see them grow up. I lost them. I lost so much. And I'm alone. Always alone. Even my worst enemy would rather die than get stuck with me for eternity. So... I'm done. I don't wanna play by the rules anymore. What rules are there, anyway? I'm the last of the Time Lords now. There's never gonna be another like me. I rule time and space. I make the choices now. It's my time. Time to get what I want."

With those words the Doctor pulls the trigger. The sound of the gunshot echoes in the silence. It still shocks Martha to see him make that choice, but not as much as she would have imagined. It's his right. It's his choice. As Cobb's body slowly falls to the ground with its lifeless eyes still staring at the Doctor, she knows that whatever happens next, their relationship has changed. Things will never be the same again after this.

The Doctor lowers the gun, lets it drop on the ground. For a brief moment he stares into the distance, then turns around to face both Martha and Donna. What the- Is he smiling? He just killed a man, killed him in cold blood and now he's smiling? Only then does she truly realize what happened today. Not two, but three people died on Messaline. Jenny. Cobb. And the Doctor. Martha looks into the Doctor's eyes. The next moment she unconsciously backs away from him. Oh my God... It's not him. Not anymore. He's gone. The man I loved, he's gone. He may look the same, act the same, talk the same, but he's gone.

Guilt start to rise up within her. I could've stopped him. He had every right to do that, but I could've stopped him. I could have. I should have. I was his companion, his friend. He saved my lives so many times and now I, I...

"I didn't save you," she whispers.

Finally Martha gives in to her sorrow and cries. How could I have been so wrong? How could I have made such a mistake? Around her people start to comfort her, but it doesn't help at all. If anything it only worsens her feelings. I didn't save you, Doctor. I could have but I didn't. And now you're lost. You're truly lost. And I think, I think the universe just got darker. She shudders. I'm afraid it got a lot darker.