The Regeneration of a Screwdriver
He was sitting beside the swimming pool staring at his own reflection. His eyes unfocused, his mind deep in thought, thinking the very same question which he had not put much attention to before, not with the Ponds keeping him busy.
However, now that they had left him to live their life peacefully on their own, he had to find the answer to the question, the question which had been haunting him ever since he regenerated: Why his sonic screw driver changed its color from blue to green.
He had regenerated many times, but this sort of thing had never happened before. "May be it's because my personality has changed" thought the Doctor at first, but then he realized that his personality changes a little every time he regenerated. The screwdriver, however, always stayed the same. So why was it that this time the screw driver had changed as well?
He took his screw driver out of the front pocket of his coat and observed it very closely; he kept staring at the green light coming out of the screwdriver, without blinking, because he was having a bad feeling about taking his eyes off the screwdriver, scared of what might come if he did so. The light from the sonic screwdriver was burning his eyes, he wanted to look away at once. Something was holding him but that's it, he needed to look away at once! The pain was not bearable any more.
The moment he did look away, Rose was standing in front of him, smiling. There was something in her smile that made his hearts pound so fast as if they were going to jump out of his mouth at any moment. He was just getting use to the sight of her when he started to have flash back of the time he had spent with her. And then images of Mickey, Martha, Donna, Donna's Grandfather, all came, and he felt his lips stretch into smile. He felt Rose's hand in his, and then he was back, back to reality.
His face was covered with sweat and his hands were shaking uncontrollably. He was lying with his back pressed against the floor beside swimming pool, and was staring at the ceiling of the roof as if observing a very interesting pattern. He got into sitting position again and once again took the sonic screwdriver which was now lying on the floor just inches away from falling into the water and observed it once more. The answer struck him all of a sudden. "Of course my screwdriver has regenerated with me," thought the Doctor "because my recent regeneration was not a normal one!"
He had not wanted to go, he hadn't wanted to change form, and he wanted to stay with Rose and all his old companions. It was as if he was forced to regenerate, he regenerated unwillingly because he had to if he wanted to stay alive. He was so emotionally attached to his previous life so regeneration would have meant a new Doctor, a new life, new companions and a new screwdriver. Because his Sonic Screwdriver was so close to him, it was like his soul. He would not be complete without it and when the previous regeneration meant a new start for the doctor. It also meant a new screwdriver, because without it the Doctor can't ever completely be new, and the memory of the old days he just saw was the proof that they both had moved on. Those memories were dying to come out of the screwdriver ever since he regenerated, and now that they had, it was time for the Doctor and his screwdriver to actually move forward and leave the past behind them.
Obviously, his old companions will never truly be gone from his mind but his new life had started – complete with a new screwdriver.