Nine
The Doctor has a diary.
At this point, he doesn't even remember when he started writing in it, or when he even got it for that matter. It's just sort of always there and even when he can't remember where he last left it, it tends to pop up right when he needs it. He suspects the TARDIS is responsible for this and acts like he's annoyed with her for it; who is she to tell him when he needs to "express his feelings?" He's not some human who needs to pay someone to listen to him prattle on about his dreams or whatever it is people do when they visit a psychologist. But inevitably, after a particularly tragic failure to save a planet or race or being, he'll find the diary by his side. And inevitably, that is when he writes. He curses at the TARDIS, but she feels how grateful he is for her gesture.
He's been traveling alone a lot lately, and it's getting to him. It just reminds him of his fate; no matter how many "companions" he has, he's doomed to outlive them all and be alone. At what point do you stop bothering to find a friend? Sometimes, he thinks, living forever is more like dying forever.
As these and a thousand other thoughts fly through his mind, he scrawls away in the diary, scowling as he forms the graceful circular glyphs of Gallifreyan. He completes an entry just as the TARDIS lands: Must go now. At destination. I've reduced myself to investigating reports of living plastic in 21st century England just for something to do. Shouldn't be anything life-changing. Nothing ever is anymore.
