A Time Lord always need people to chill with, he'd be lost without them!
"Some leave, or they find someone else." Martha Jones.
"Some of them forget me." Donna Noble.
"In the end, they break my heart." Rose Tyler.
If you want to break it down more Martha Jones is the Doctor's Mind. She's really smart, a medical doctor herself. She's logical, not very brave or rambunctious. She's a Ravenclaw to boot. Of course, she's desperately in love with him, and a bit jealous of Rose, but she keeps quiet and helps him out of every sticky situation.
Donna is the Doctor's Soul. She is sympathetic and always sees the big picture. Most importantly she keeps the Doctor grounded when he's upset. A Hufflepuff, Donna isn't in it for the risk, or because she loves him, but because it's important, because she can help him, and because she can make things better.
Rose Tyler is the Doctor's Heart. She is charming, loving, and has a huge sense of humor. She keeps things excited, and is devoted like none of the others. A Gryffindor at heart, Rose would never back down from a challenge, and can save the world in the strangest ways. It's like all she has to do is stand there, and everything is a bit better.
There's Captain Jack too. Mr. I-flirt-with-everyone.
Jackie, Rose's mom. She's usually understanding.
We can't forget poor Mickey, who always gets the short end of the stick.
And Sarah Jane always comes back.
One last thing, this is the most beautiful Doctor/Rose fanvid ever. I hate fanvids as a general rule, but this was beautiful.
Long post is long. Have a very good day. I'm going to go have pie now.