Ianto stared at the two of them on the CCTV monitors. The Doctor and Jack. The two of them working in tandem, passing things back and forth to each other. It was like watching a well oiled loom. Back and forth, back and forth, until they were done.
He couldn't hear them, but he could read their body language. Jack was in full battle mode, his face and limbs conveying the familiar, desperate desire to bring an end to this enemy. But what shocked Ianto was that the Doctor moved in exactly the same way.
The set of their shoulders, the sweep of their limbs, the angle of their jaws, even the way their coats billowed as they ran. The two men looked nothing alike, yet to Ianto they looked like twins.
The Doctor and Jack Harkness, twinned in time.
Ianto watched as Jack ran to the door, carrying a long metal lightning rod. This part was very familiar. Jack would charge out, set up the saving-the-world-device and then watch as his plan was set in motion. Ever the dashing hero.
But then Jack turned. He turned. He looked to the Doctor, his face questioning and just a little frightened. Jack's face was frightened!
But the Doctor just looked back at the immortal man. Ianto saw his lips move as he spoke. He only said one sentence by the look of it, and not a very long one. It was enough. Jack once again became the dashing hero, full of the confidence that was uniquely his own.
When the plan was followed through and the aliens fell, Ianto realised that it was with good reason that Jack followed the orders of this ancient and mysterious Time Lord. Though the Doctor and Jack were twinned by their heroism and their pain, the Doctor was the dominant twin. The elder sibling who taught his brother everything he knew.
Jack was who he was because of the Doctor. Everything he knew about being a hero came from this man. His twin.