The Long Way Home(Doctor Who/Steven Universe crossover)

Sabotage

A lot of things had been going through Pearl's mind since this hectic day began. One thing was clear, however, and it was that the Doctor knew when something needed to be done. She also knew that she needed to get home and the two of them needed each other to make that happen. Pearl thought hard about the Doctor's question before replying, "I wish that I knew. Only the Gem who established this base- the one who created its Crystal Heart- can construct and alter the interior dimension within it. Who could that be?" she wondered allowed to herself.
"You tell me," the Doctor responded calmly. Pearl thought for a second.
"Well, since this Citadel seems essential to running things around here, what with its connection to the Cluster, and its direct communication/warp access to Grey Diamond...I would say...Grey Diamond."
"Well, what about these tubes- the veins of the heart," the Doctor asked.
"Doctor, I'm afraid this is getting a little out of my field of expertise," Pearl spoke with a shrug.
"Of course," the Doctor responded calmly. "You're a rebel, and something about rebels like us is that we mostly specialise in wrecking things, wrecking things to make things more difficult for our enemies," he remarked, sparing a glance at the wide gap in the corridor. "Or for ourselves."
"I certainly hope you have a point to what you're saying right now," Pearl replied.
"The point is that there is one thing that we can control in this crazy place- the things we can wreck."
Pearl went back to searching her brain for an idea that could give them their next little push.
"All the tubes in the Citadel are connected to the Crystal Heart- that is their source", Pearl reasoned. "The Heart is connected to the Cluster." As she continued speaking her eyes looked doubtful, but her voice still sounded controlled and matter-of-fact. "If the Cluster's link to the Heart were to be permanently severed-"
"The Heart could be directed to link itself to the TARDIS instead", the Doctor threw in suddenly, earning a stunned stare from Pearl.
"Yes, I suppose, the Citadel isn't exactly linked up to your shi- your TARDIS."
"The veins run deep, deep through the ground of this planet and I'm willing to bet that the TARDIS is still right above them."

The Doctor darted his eyes across the the three dimensional landscape of the Citadel that lay in the empty space, tracking out a path through the labyrinth like Citadel interior, his attention stopping at a spherical shape that connected to what he pointed as the Crystal Heart's chamber.
"First of all, we need to get back to the main hall," he told Pearl. He gazed up at the section of veins in the corridor ceiling that remained intact. "At least we wont be getting lost."

A few more seconds of mental mapping and Pearl and the Doctor had worked out a path to the spherical shape of the hall. Exactly one second after that, the Doctor had turned on his heel and began sprinting down the remaining part of the corridor, ready to charge into whatever mad idea he had next.
"Wait," Pearl quickly called out. The Doctor skidded to a stop. Correction, he was almost ready to charge on. "How can you be so sure that the TARDIS will still be where we left it?" The Doctor just responded with, "You'd be surprised how much of an effective disguise a big blue box in the middle of nowhere actually can be."
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Elsewhere, about 8 trillion light-years away from Earth, Grey Diamond's throne room was being disturbed by callous, indignant shouts. Between a Diamond and her most trusted but oh so sensitive general.
"My Diamond," said Star Quartz. "I'm telling you that I only request a small fleet of soldiers. Perhaps a Roaming Eye or two as well."
"I wont go sending valuable forces of Homeworld to Earth just because you can't keep a human or a defective Pearl under control," Grey Diamond replied, coldly and officiously.
Star Quartz glared at the very scared and very confused Azurite who stood behind her, as if expecting some kind of support.
"I swear I'm just an innocent bystander in all of this, My Diamond," stammered the anxious Azurite.
"Star Quartz, you're not thinking clearly," said Grey Diamond. "We will deal with this breach in security in time, but I'm afraid I will have to discharge you. You're incompetence could be more threatening to this colony or this Authority than any rebel at this rate."
"G-Grey Diamond," piped up Azurite. "If I could add anything right now, it does seem unusual how the Pearl could have avoided capture and survived ever since the Earth colony was built. I-I suppose it would be possible that other rebel Gems may still be on Earth somewhere, aiding her."