She gazes at him with a grin on her face. "Where are we?" she asks.
He smiles widely from ear to ear. "Don't know…" he answers. "Should we have a look?"
They're both racing for the door as a response. He allows her to yank the door open before him, eager to see the grandeur of a new world. The smell of acid, metal, and burnt wood wafts into the TARDIS as the Doctor senses a foreboding. Leave, it says. Leave now before it's too late!
"Doctor, something's wrong." Her voice is soft and frightened as she steps out onto the soft layer of soil.
He steps out as well, breathing in the polluted air filled with death and war, a scent he is accustomed to this far into his old Time Lord life. "You're right," he finally says. "Something's definitely wrong." And he knows it; he feels it, but it's not exactly the gut instinct that his companion is feeling right now. Something, in time, is telling him that this is an event he cannot change—a fixed point in time.
"Come on, Doctor!" she shouts, grabbing him by the hand. "We have to fix all of this!"
Following her closely, the Doctor allows her to take the lead, charging headlong into the city of tall, metal skyscrapers raining flaming wreckage onto the ground. The sky is an ugly swirl of maroon, orange, gold, and black, with sickened green and grey clouds hanging about. The ground beneath the Doctor's feet is soft, worn down by what feels like years and years—up to hundreds of thousands perhaps—of destruction and demolition of what was once fresh dew grass with a hint of minty evergreens.
The air is thick with the pungent scent of fire and death, filled with the roar of crumbling buildings and screaming people. He wants to take her hand and drag them back into the TARDIS and leave, but he knows that something in this era, at this time is about to happen, something important and irreversible—he just doesn't know what.
They run through the desolate city into what appears to be some sort of office building, the largest building by far. It's a triangular edifice made entirely of what looks like glass, but with a swift scan with his sonic screwdriver, the Doctor realizes it's a metal not found on Earth. It looks like glass, shatters like glass, shines and tints just like glass, but it's not glass—it's a metal called vemet. It's non-flammable and extremely thick; however, with the right pitch, the entire building can shatter.
"Doctor!" he hears her scream, and he rushes to aid his best friend.
She's climbed up the first two flights of stairs out of what seems like thirty. The floors are that same metallic glass material, but that's not what worries the Doctor. He's concerned about his comrade's safety, for looming ahead of them is what the Doctor knows as a Staxin, a creature that lives off of death and heat; one touch of a Staxin drains the body of all energy and heat, rendering one dead.
Staxins appear as tall, slender humanoid forms with no defined facial features; their exterior radiates heat and emits an orangey glow. Due to the usual high frequency in their voice, the Staxin can't speak or else the building would shatter. However, the Doctor can convey none of this to his partner who stands there gawking as his brain processes the information in less than a billionth of a second, but that's fine, because once the Doctor's done thinking, the Staxin makes its move.
"Duck!" the Doctor screams, pulling her down into a crouching position as the Staxin swings its arm at them.
They barge past the fiery figure and bolt up the stairs. "Don't let them touch you," the Doctor warns as they climb the stairs, adrenaline pumping through their systems.
She nods slightly, following the Doctor closely. "Where exactly are we going, Doctor?" she asks. "What are those things?"
"Staxins—creatures who live off heat and death; one touch, and that's it, even for me—especially for me. The more energy the better, and I'm just bursting with it!" he exclaims. "As for where we're going—to the top!"
"Why?" she says, nearly tripping over her own feet in her haste.
"I haven't quite figured it out yet, but, you see, Staxins are creatures that always take too much, like the little kids at Christmas who take more turkey than they can eat So, when they can't consume the energy they take, they store it away as a surplus."
"So why at the top of the building?" she asks.
"Don't know," he answers honestly. "But this entire building is made of a metal that they can't talk around, quite literally. However, this building is also acting as chisel. Beneath here is an inactive rift, and they're trying to crack it open."
"Why?" she asks.
"The energy. Imagine the energy that will spill out of it! There's enough for an eternity!"
"Enough to feed the entire species."
"Children, wife, and all."
They reach the top level without any other obstructions. The Doctor works quickly to unlock the metal door with his screwdriver, pulsating blue flashes as he adjusts the settings. He yanks the door open as she screams, "Doctor!"
He whirls around and finds the Staxin behind them. Gripping her wrist, he pulls her beyond the doorframe and slams the door shut. She becomes stunned. "Doctor…"
Looking around, he realizes that they're outside again, on top of the roof. Around them are hundreds of Staxins, all staring at the intruders. In the center of the platform is a gigantic sphere of pure, raw energy, souls stolen from their physical bodies, still screaming for help.
"Let them go!" the Doctor screams, about to run forward, but he stops quickly as the Staxins take a step toward him and his companion, threatening to kill them. "What do you want?"
"You already know, little man," a Staxin responds, a voice distinctly female and soothing.
"The energy from the rift," he states.
"Yes," the voice answers. "We've waged war on this planet for thousands of years now for control, and this shall be our reward."
"But you're the Staxin! Brilliant, smart creatures who absorb whole stars! Why choose this planet to live on? Why do you need the rift?" The Doctor was hysteric.
"Because with the energy, we will live forever, never dying, and without the need to maintain a body."
An earth-rumbling shudder blasts throughout the building as the sphere suddenly expands.
"Stop this right now!" the Doctor screams. "I'm warning you! I don't do second chances, and you will leave this planet now! I'll find you a new home! I can help!"
"Foolish little man," the Staxin laughs. "You cannot stop us. You cannot help us! No one can!"
"Try me," he growls. "My name is the Doctor. I'm a Time Lord from Gallifrey, the last of a dead species from a burnt up planet. If anyone can help you, it's me."
The Staxin steps toward the Doctor and raises its hand in attack. "No one can help us," it snarls.
"No!" she screams, pushing the Doctor out of the way.
He panics and runs to her side. From her slender neck, a grey-blue welt begins to spread, sucking the color from her face and arms.
"No, no, no!" the Doctor screams, cradling her dying body in his arms. "You can't die… Please…"
She grins wistfully at the Doctor. "I'm sorry," she says. "I said forever… I'm so sorry…"
Suddenly, he feels an abrupt connection to his time instinct and this event. This is the fixed point in time—the death of his precious companion. Rose Tyler's death. The Doctor puts his forehead to Rose's and sheds a single tear before he hears her breathe her last. His hearts feel like they've been encased in ice, set on fire, and then stabbed viciously. He wants to mourn her, to revert to that little kid crying in the corner of the room and everyone ignores, but now is not the time. This is the time to punish the criminals.
He points his sonic screwdriver at the console next to the sphere of energy and says, "No second chances."
The sphere suddenly shrinks drastically, collapsing in on itself, and the voices cheer, whispering in joy. The building rumbles again and the Staxin panic.
"That's right!" he screams. "Run! Run for your lives!"
The guilt and pain of committing genocide once again flies past him, leaving him unaffected. He can't forgive them. He can forgive the Daleks for wanting to destroy everything—they were programmed to do it. He can forgive Davros for creating the Daleks—they were his most brilliant pieces of work. He can forgive the Time Lords for being beasts—they paid their price for it. He can forgive the Master for his constant wanting to own the universe and everything in it—the perpetual drumming in his head created by the Time Lords led him to it. But he cannot forgive an insolent species that refused to listen to him and kills his best friend and love of his life.
Turning on his heel, he picks Rose's limp body up in his arms and descends the staircases. He heads back to the TARDIS calmly, and once he's inside, he lays Rose's body on the chair and sighs heavily. He doesn't shed tears though; he steers the TARDIS away from the planet… and then watches it burn. It reminds him of Gallifrey, and it reminds him that he's not just the Doctor, man who heals people. He's the man who has no mercy.