I've been reading quite a lot of Doctor Who fanfiction today and it's got me thinking. I've come across Rose/Ten, anti-Rose/Ten, Rose/Ten.5, River/Eleven, Romana/Four, Sarah Jane/Four and plenty of other ships, and it's occurred to me that although I'm happy to read just about any of them, I don't have a Doctor Who OTP.
There's plenty of people on the internet who feel that Rose was the Doctor's soulmate; or Romana was his soulmate and the only reason he ever cared about Rose was because of the aftermath of the Time War; or in fact Martha was his soulmate and he just didn't realise it because he was so hung up on Rose, and loads of other stuff like that. Personally, I don't think the Doctor should really be shipped with any single one character above any of the others that he's shown romantic inclinations towards. I think he's capable of loving more than one person at a time, in different ways but with the same intensity, and I don't think he'd ever choose between them if it came to having to spend his life with only one of them. Honestly, I think he'd choose to be alone without any of them rather than be forced to pick just one.
I know that may sound odd, knowing that he does get immensely lonely and that's the reason he has companions in the first place, but he's shown that he's capable of leaving his companions when he knows it's the right thing to do, and he would feel that it wouldn't be right to be with just one of them forever when he cares about the others just as much. He loves all of them in different ways, and out of all the people he could potentially be shipped with they all have different things that would make them a great couple, but I don't think any of them really takes precedence over any of the others.
In my opinion, the only 'person' that understands and accepts the Doctor in such a way to set their relationship apart from the others would be the TARDIS, but since the TARDIS has only ever had human form once, shipping him with a blue box would be a bit odd. So I will continue to quite happily ship him with anybody provided it makes sense and goes along with canon (mostly Ten/Rose, as this is what I'm most familiar with) but I really don't think any one romantic pairing for him stands out above the others.
I like Ten.5/Rose because I don't really think of Ten.5 as being the real Doctor, just a human version of his tenth incarnation, and since Rose was the one he truly loved throughout his tenth incarnation then it makes sense that they end up together. But I still don't think there should be any one true pairing for the real Doctor: it all depends on which incarnation he's in, as his emotions change over time and although he may feel differently about his companions, there are certain ones (like Romana and Sarah Jane) that I don't think he will ever stop loving.
If you really pushed me to say what my OTP was I'd probably say Doctor/TARDIS. That's the only relationship that remains constant and unchanging and isn't affected by what incarnation he's in or who else he may be travelling with. But like I said previously, shipping the Doctor with his spaceship is just a little odd. So I suppose what I'm really saying is that I ship the Doctor with everybody within reason, but at the same time there's nobody I truly ship him with. Honestly, I don't think he's meant to be with just one person for the rest of his life or feel like he wants to be. He's better suited to having a large number of loyal and devoted friends, and although he may have romantic feelings towards some of them, I think the fact that he's capable of loving all of them differently is what stops him from wanting to be with just a single one of them forever.