I had quite a difficult time with this one. Actually, I had a difficult time picking most of these, but this one especially I went back and forth on. It was either gonna beCaptain Jack Harkness, Donna Noble, the Ponds, or Clara Oswald. Even though I love Cap’n Jack and Eleven’s friends, Donna’s just a better companion. I even love how she winds up joining the Doctor. She actually turned him down at first. We went a whole series without seeing Donna Noble after she walked away at the end of “The Runaway Bride.” I was ecstatic when she returned in “Partners in Crime” and became a full-time companion.
See, I feel like the companion’s role is to be a foil for the Doctor. Not someone to praise or adore him, but someone to call him on his crap and keep him humble. And she did that by being Ten’s opposite. Where he sought vengeance, she pleaded for mercy. When he wanted to go it alone, she stuck with him. The Doctor was wonderful in her eyes, but he was never perfect. Donna was hilarious, and even though she was a difficult person to get along with, she genuinely wanted to do good in the world.
I was legitimately sad when she left (especially with how she left). Thankfully, the Ponds joined Eleven soon after, so I wasn’t without good companions for too long.