With Clara, the show has had an unusual turn in the Doctor-companion relationship in that she's been written as almost the entire reason for the Doctor's existence. In Listen, for example, she's the one who tells him as a child that fear is a superpower, while in The Name of The Doctor she saves his history from being rewritten by the Great Intelligence. She's even partially responsible for his increased number of regenerations. While that makes for an interesting turn of events, it also negates some of the Doctor's strengths. The Doctor just flails around being "an idiot", as he says, as Clara stumbles in and fixes everything. While companions should certainly be capable people, it's when they and the Doctor do not have a balanced relationship that the storylines lose their potential emotional heft. The Doctor and Donna had one of the most symbiotic relationships compared to his other companions. When the Doctor is alone, the Doctor gets himself into more trouble. Without someone to reign in his more merciless side, he can sometimes overreact, like he did with the Racnoss in The Runaway Bride before Donna told him to move on. She was also not one to immediately swoon over his charm. What she liked about him was that he made her feel important, something she desperately wanted in life, and when that importance was combined with the spirit of adventure, it was essential to her that she carry on travelling with him. She's one of the few companions who didn't choose to leave.
Sara Habein is the author of INFINITE DISPOSABLE. She is a staff writer for Persephone Magazine, and the editor of the Word Riot blog. Her Doctor is number Eight, but the Twelfth is right behind.
