She can only think about how she is going to kill the Dalek.
From the moment she sees it, its tentacles wrapped around Aaron’s body, not dead, very much alive and hurting yet another person.
She is going to kill it, no matter the cost.
The Dalek is holding on tightly, secured to Aaron and not willing to let go, and it so easily believes her when she says she’s going to take it to the Dalek fleet.
Honestly, by this point, they should know better than to trust the Doctor.
So she goes, takes it onto the TARDIS with the rest of the companions, all tagging along, and plugs in the coordinates for a supernova that’s got a vacuum corridor just the right size to take the Dalek and probably, maybe, not Aaron and they’re off. She figures this has got at least a 50% chance of not also killing Aaron.
Part of her, a small part but growing with ferocity as she tries to find new ways of saving humanity, thinks that maybe, maybe it wouldn’t be so bad if Aaron was killed too. One human life for one Dalek, a human that’s hurt one of her friends nonetheless. Would it really be a loss in the world for him to die too? To get rid of a being that is so evil?
They’re on the TARDIS and she flings the door open, shocks the Dalek into stumbling back a few steps and they are both, Dalek and human, nearly out the door before something in Aaron seemingly starts to fight back, grabs the wall and holds himself desperately from flying in too.
“Dad!” She hears Ryan scream, hears Yaz tell her to just Do something! but she can’t, is too focused on just getting rid of this creature, plunging it into the unforgiving abyss that is a star going supernova.
She tells herself that she’ll just wait a few more seconds and then close the door - figure out some other way of getting the Dalek off Aaron but a few seconds turns into a few more and the vacuum corridor is increasing, she doesn’t know how Aaron is still holding on.
The TARDIS is shaking, straining against the gravitational pull of the star and the exponentially expanding vacuum corridor and well, she figures, this will be over soon enough, one way or another.
(She could close the door - could save Aaron and the Dalek and find some other way of protecting her friends but then there is a chance that the Dalek could escape, could leave and how is she going to do that)
There is commotion, she hears some shouting but she is too busy in her own head, doing calculations, running numbers through equations trying to estimate the maximum the vacuum corridor can extend before they get sucked in too, how long they can wait before Aaron’s grip inevitably gives out. Just how long she has to wait.
She’s doing this, not paying attention because she never claimed that she could do everything, that she was perfect, she’s only Time Lord after all (except, of course, when she does claim that she’s perfect, when she saves the day with nothing but a paperclip and her sonic screwdriver. This is not one of those times).
She’s not paying attention to the shouts in the TARDIS. To Yaz screaming Ryan’s name as he runs towards his dad, tenacious relationship forgotten and with the thought of family only on his mind. Misses Graham’s few steps forward as well, as if to stop Ryan or maybe just protect him.
Misses the way that Ryan reaches his hand out to try to get his dad to take hold, to drag him back into the safety of the TARDIS.
Turns around in time to very much not miss how right when Aaron seems to just reach out to grab hold of Ryan’s hand, the Dalek still controlling his body then forces his other hand to let go, and there they go. Flying off into the star, sucked in by the gravitational pull and they’re off.
A snap of her fingers and the doors close, shut behind them and Ryan is instantly at the door, screaming, clawing at the door as though he can bring his dad back if he just tries a bit harder.
“Doctor! We need to go get him! We need to fly to him!” he shouts, turning to face her.
“I can’t. The TARDIS will get sucked in by the star and then we’ll all die. I’m sorry, Ryan. He’s gone.” Her voice is like steel, void of any emotion, and she turns back to the console to fly them all safely back to Earth, threat eliminated.
She hears Ryan trying to open the door, and thanks the TARDIS silently that she keeps the doors locked, preventing him from opening them and doing whatever foolish act of bravery he might be inclined to do now. She’s not sure if she could bear to lose anyone else.
Hears as Graham and Yaz go to Ryan, comfort him in the so, so human way that they know how to and god, doesn’t she wish that she could be just a little more of what she knows her companions need.
It was, of course, worth it, wasn’t it?
Sacrifice a human to kill a Dalek, the most evil creature in the universe. The Dalek could have, would have killed many more if she let it go. Numerically, she was doing the universe a favor.
“We need to go back! You’ve got a time machine, we need to fly back and save him, bring him back, something!” Ryan has moved from the door and closer to the console, looking at her with a tear streaked face and something far more dangerous. An unwillingness to accept the past.
This is what always happens when she has humans travel with her. Some tragedy occurs and they believe that she can just change the past to make it right.
“I can’t, Ryan. The past is set in stone, there is nothing I can do. If we go back, it would cause a paradox; if he was alive there wouldn’t be any reason for us to save him,” she’s trying, she’s trying so hard to make him understand. That this is out of her hands.
“I’m sorry. I wish there was something, but there isn’t. There is nothing I can do.” She says, forcing herself to look at him. Just killed a family member, after all, wouldn’t be fair for her to simply retreat back into herself, away from all these human emotions, in to the safety of her own isolation.
“Doctor, there must be something you can do? Some way we can change it?” Yaz says, and her heart nearly breaks hearing the quiet plea in Yaz’s voice, filled with so much hope that the Doctor can just fix it if she just tries hard enough. Oh, so much like the Doctor’s past companions, they just don’t understand that the Doctor can’t fix the universe, no matter how much she tries.
She just shakes her head slowly, watches as Ryan’s face crumbles again and God, does she wish she could do something. The laws of time are set in stone and there is nothing that she can do to change that.
“Why didn’t you close the door, then? When he was nearly falling out? We - you - could have found a different way to get rid of the Dalek. Bought us some time at least.” Graham speaks up now, his arm wrapped protectively around Ryan.
“I couldn’t risk it - I couldn’t have known the Dalek was going to do that, though. Figured it wanted to be in the ship as much as Aaron did. I didn’t think that the Dalek would take Aaron with it.”
“Really, Doc? You said this was the most evil creature in the universe and you wouldn’t have thought that it wouldn’t have sacrificed itself just to bring a little more pain into the world?”
She feels herself growing angry - for as much as she loves her friends they just don’t understand, do they. Don’t have the same experiences that she does, haven’t lived as long. Don’t know the extent that the Daleks are capable of.
“You have no idea Graham. I know exactly what they were going to do. I know how they think, how they act, and I know that if I let this one get away, who knows what would have happened. How many other people would have died. What, was I supposed to save one person and risk the lives of millions of others? Was he more important than millions of people?”
She realizes she’s gone too far as soon as she stops talking, when the rest of her companions are seemingly stunned into silence. A part of her is pleased - good for them, she thinks, for finally understanding the choices that she has to make. All the time, without thanks.
“He was to me,” Ryan responds, quietly.
But you didn’t even like him before a few hours ago! She wants to scream, he hurt you! How could you be this upset about it?
But the Doctor knows she doesn’t mean it, knows she’s just finding a way of avoiding that she did something that was wrong, that she shouldn’t have done.
“Take us home, Doc. Please.” Graham says. Ryan nods mutely behind him. Yaz says nothing, just stares curiously at the Doctor, as if trying to understand the creature that stands before her.
The Doctor says nothing, turns around, plugs in the coordinates for Graham’s house. She had memorized them, because they’re friends and she does that with her friends, remembers their space-time address and doesn’t forget it. (Seems like she might not be using that, any time soon. With the way that Graham is looking at her, face set in a frown, and how Ryan seemingly can’t even bring himself to look at her).
They make it to Graham and Ryan’s house, she lands gently, taking care not to land on any other piece of furniture that’s lying around.
“We’ve landed,” she brings herself to say. She hopes they’ll come back.
“Yeah. Alright. C’mon, Ryan. We’re going home.” Graham says, leading Ryan towards the door. The Doctor can’t bring herself to do anything other than stand there, watch them leave. It’s their choice, it’s always their choice, and she knows she went too far this time. Isn’t sure how she would forgive herself, let alone ask them to forgive her.
Right before they open the door, Ryan turns around to look at the Doctor.
“I don’t hate you, you know. I blame you, right now, but it’s what you thought you had to do.”
The Doctor just nods in reply. How to condense the history of her species, of the largest war the universe has ever known, into one sentence. What could she even say to stop them from leaving, “I’m sorry I killed your dad, who you were just starting to get reacquainted with, but I also was about to kill my entire species because of the Daleks, so can you blame me?”
She’s not sure if that would go over too well.
“Are you gonna come back?” Yaz asks.
“I’m not sure. We’ll keep in touch, let you know if we want to fly again. I think we need to take some time off, now, for a bit. It’s so dark out there, it’s time to take a step back, I think.” Graham replies. “Maybe you should do the same, Doc. Reevaluate what you think is right in the universe.”
“Right… yeah, that’s understandable. Right. Alright. Well, I guess I’ll see you, then. You’ll find me again if you want to see me. I’m hard to get rid of, I’ve heard.”
Ryan and Graham nod, open the TARDIS doors and step out.
“I’m sorry.” She says, as they leave, words coming out softly. They don’t respond, the door closes. She’s sorry, of course, never wants to make decisions like this, to cause this kind of hurt or pain in her friends.
She’s sorry, but she’d do it again if she needed to.