The Butterfly Effect
This is set in series 4 right before the episode of "The Fires of Pompeii"
The TARDIS materialized and Donna yanked open the door as soon as it solidified. She walked out but then froze.
"Ancient Rome my ass, your driving is terrible space man!" complained Donna with her arms folded.
The Doctor, having heard Donna's remark, eased up more. He hadn't wanted to go to Ancient Rome because being there reminded him of the last time he had been there, and that was with Rose. But he had sucked up and not said anything when Donna said she wanted to go to Rome. However when he realized that they weren't in Rome anymore he felt relieved. When he walked out of the TARDIS however, he froze. They definitely weren't in ancient Rome. They appeared to be in a Graveyard, 21st London graveyard by the looks of it.
"This is London!" Donna said glaring at Doctor
"When are you? This looks like my time, is it?" asked Donna looking at him for confirmation.
The Doctor concentrated on the timestream and it confirmed that indeed they were in 2008.
"You are morbid space man. There is a difference between Ancient Rome and a graveyard! Why the hell are we here?" asked Donna frowning as she looked around.
"I am not sure..." the Doctor frowned as well. Usually he was never far off, but this time the difference from his coordinates and actually landing was too big.
He closed his eyes and communicated with the TARDIS.
'Why did you land me here?'
The TARDIS did not give him any reply. He found it alarming because from what he could sense TARDIS was distressed and depressed for some reason. Worry, anguish and concern seeped off her and assaulted him telepathically. It was so intense that he pulled back and snapped his eyes open.
"What's wrong?" he asked while touching the TARDIS in concern.
He had never gotten such a strong reaction from the TARDIS before. She was extremely sad.
When Donna noticed that the Doctor's attention was fully on the TARDIS she rolled her eyes and walked away from him to look around.
She knew his moods, when he had that expression in his face that meant that he was busy, too busy. Probably so busy that he forgot about her. Although she has been travelling with the alien for only few days, she had gotten hang of his erratic mood swings. He appeared to be always jolly and happy but she wasn't stupid. She could see that his smile never really reached his eyes. He seemed haunted and lonely. But yes he was giddy. She had also learned on not to mention Rose Tyler's name. The first time she had, his face was blank and he hadn't said a thing. That had scared her more than his rage when he faced the Racnoss. He had tried to blow his reaction off though, forcing a small fake smile but he was incredibly quite the whole trip that time.
She knew the signs. He was in love, badly. It actually made him wonder what ever happened to Rose. What happened so bad that the Doctor was so haunted. While thinking, she was so lost in thought that she did not notice a headstone in her path until she tripped over it and fell flat on her face.
"Damn it!" growling in anger she stood up and tried to brush off the dirt from her top. When she looked down to glare at the tombstone she immediately froze in horror and gasped outloud.
When he didn't get any coherent answer from the TARDIS for whatever was causing her the distress, the Doctor gave up and decided to look around whevere he landed to get an idea what was causing her this distress.
It was then he realized it was very quiet. Very quiet and he knew very well that his newest companion was never quiet for this long.
Worried that she got in trouble already the Doctor started to look around but then immediately spotted Donna. She was standing ten feet away from him infront of a grave.
He then walked towards her.
"What caught your interest?" he asked curiously.
When Donna turned to look at him he froze because her gaze was filled with sympathy and sadness.
"Donna?" he asked, this time with concern.
"I didn't know...I am so sorry" she said.
The Doctor looked at Donna incredulously
"Sorry for what?"
But Donna didn't say anything. Confused the Doctor looked at the gravestone that Donna was seeing and immediately froze up.
Because on the gravestone it had Rose's name and the date was "1986-2005"
As if burned, the Doctor violently stepped back.