When he first meets Jenny, it takes him a while to get over the fact that she is the doctor's daughter, and yes, he means it in all caps, c It's too mind-blowing for him not to. . The Doctor jumps out of the Tardis, and there she is, all charming and with a dazzling smile, a confident walk. A wave to Martha, then her eyes explore for her. She shakes Jack's hand, they measure each other, without any sympathy or dislike. Jenny loves Mickey, they respectively share details about their favorite Big Fucking Guns. Jack winks at him when the Doctor isn't looking. She rolls her eyes, but secretly smiles at him as she leaves. A shared message. A challenge. The second time he sees her, she immediately starts flirting with him. Jack does his best to return the favor, dancing between the Doctor's incredibly dark looks. She is sweet, young and sexy as hell. Despite the fact that she defeats him in an impromptu fight. The Doctor is more than a little proud when she emerges almost unscathed, while Jack has to lean on Gwen for support as she delivers him to a sneering Martha. This is the last time he brags about his strength and endurance, when GI Jenny is around anyway. The third time is a crisis. The world has gone to shit because of some alien threat or other and the Doctor must step in to stop the end of the earth again. Nothing new there. But Jack finds himself taking his orders. She knows more about military tactics than he initially thought. He doesn't really understand why he submits to her. Is it the fact that she looks like the Doctor? That unwavering look she casts on him? That look of utterly dark determination? He doesn't have time to think beforehand, and even in the middle of the paper. “What do you think?” It seems pretty normal, at least from the outside. Much like the Doctor's Tardis, it is a simple-looking wooden box, with a glass door on one side. And yet, there appear to be strands of metal around the entrance, growing into the walls themselves, like some sort of metal vine. “Cool,” he said. Jenny is visibly happy. “But why emerald green?” Jenny shrugs and says, "It was one of the colors, of the ball of light, of the terra forming device, back when I was born. When I died." Jack nods, remembering the story she told him, of being born in the war, with Messalina and Hath and being shot in the chest. “Huh,” he said. “So…” Jenny steps back and opens the door. “Are you ready for an adventure, Captain?” Jack smiles and pulls his coat closer. "You bet, GI Jenny." And he goes with her and follows her into the future. The End