I knew that they were looking for a new Doctor, but just reading an article now mentions that Pearl Mackie, who is playing Bill, will be leaving at the Christmas Special. Trying to make everything new for the new writer. Here’s the link to the article, it mentions the companion near the end of it – http://www.doctorwhotv.co.uk/rumour-13th-doctor-a-dashing-male-actor-in-his-30s-83719.htm
Anyways, Here is my vote for who should be the companion – Osgood. I’ve been rewatching series 9 as I just purchased it on Blu-ray. Anyways, at the end of the Zygon invasion 2 parter, The Doctor asks Osgood if she wants to come along, to travel through time and space. You can tell that she’s very excited but the offer is declined, saying she needs to stay to protect the boxes, protect the planet,
There’s two Osgood’s though, the one that was Clara changed into Osgood the first Zygon Osgood was killed. So why not have the real Osgood travel through time and space with The Doctor and the Zygon Osgood stay on Earth to protect the boxes. Problem solved.