Time was stolen
Jack Harkness believed that to fall in love was to be destroyed, his heart was stolen. Ianto Jones believed that to fall in love was to be saved, his heart was given.
Jack Harkness was a man with many lives, and sometimes falling in love couldn't be helped. He would be instantly connected to certain people that he met, love at first sight. Jack did not feel this way when he first looked upon Ianto Jones, so he believed he never would.
Ianto Jones was a man with a heavy heart, plagued by the war that killed his love. Ianto knew what it meant to lose a lover, to lose all hope of loving again. When Ianto first met Jack he did not soothe the pain of his memories, so he believed he never would.
Jack Harkness never thought of the consequences the first time he kissed Ianto Jones. It was a delicate brush of his lips against the youthful mans. He was not seeking love, but craving the closeness of another.
Ianto Jones never thought he would fall in love with Jack Harkness, but on the night Jack had first kissed him, he tripped, stumbled and fell before he could even attempt to stop himself. He was not seeking love, but it he had succumbed helplessly.
Jack Harkness lay awake some nights, haunted by the faces of those he lost. Some faces of his lost lovers now blurry, as if he could no longer hold on. Ianto's eyes would flicker open as he lay beside him, he looked at the man with too much loss to ever truly love again.
Ianto Jones lay awake some nights, crying. Silent tears would escape from his eyes as he looked over at Jack; the pain of his unrequited love was almost unbearable, but he could never let him go. Jack would realize, and wrap an arm around Ianto, as an apology.
Jack Harkness looked down into Ianto Jones's eyes and begged him not to leave him. Jack cried leaving this world again, knowing the man he needed, would no longer be with him. He no longer wanted to face life, if it meant a life without Ianto Jones.
Ianto Jones looked up into Jack Harness's eyes and begged him not to forget him. Ianto felt the earth closing in around him, knowing that the man he loved would no longer with him. Ianto was torn apart from his life, leaving Jack Harkness alone.
Jack Harkness realized he was wrong. Somewhere along the line, he'd fallen harder for Ianto Jones than he ever had for anyone. Jack sobbed over the body of the man who had broken his heart. It was too late to rewrite the last words, and Jack fell into despair.
Ianto Jones realized he was wrong. Somewhere along the line, he'd become the single most important person that ever would happen to Jack. Ianto Jones saved the world, and smiled softly in knowledge that he was special, he was important, he was memorable.
Jack Harkness told Ianto Jones that he loved him. Jack Harkness knew that he would never feel this way again. It was a desperate act to try and save him from death. He couldn't rewrite the time that he thought was stolen from them.
Ianto Jones told Jack Harkness that he loved him. Ianto Jones knew that he was always going to stay with Jack Harkness. It was a selfless act to try and save him from death. So he made Jack Harkness go back, and gave him the time he thought Jack could still have.