The Doctor’s travelling agreement with Clara is much the same as the one that developed with Amy and Rory Pond. Rather than having a constant companion the Doctor picks them up (on a Wednesday for Clara), takes them on an adventure and brings them back to continue their lives.
This is a dramatic contrast to the format of the early years of the show. Several companions were defined by their desire to get home, something that the Doctor had a hard time achieving.
Other companions were recruited because they had nowhere else to go. They travelled with the Doctor because it didn’t matter where they went. They hadn’t put their lives on hold to have adventures, they didn’t have loved ones who were waiting for them.
Deciding what the arrangement is between the Time Lord and their travelling companions can have a huge influence on the feel of a campaign.
If the player character has a destination in mind, such as the year they left or Heathrow airport, then it must be agreed how important this fact is. If this is the only motivation for a character any adventures along the way could be a distraction and at worst an irritation.
The worst case scenario is a companion who immediately wants to leave, in the hopes that next time they’ll arrive at their desired location.
This can be mitigated by giving a reason for them to stay long enough to have an adventure. The TARDIS could need time to get its bearings to improve their chances on their next trip or they could need to acquire much needed supplies.
Their destination can take them tantalisingly close to their location. They might arrive in the right place but the wrong year or the right year but the wrong planet. They might even miss their target by just a few years.
Eventually the TARDIS will take them where they were trying to go. Will they leave or decide to stay? They might leave only to realise they want to keep travelling and seek out the Doctor once again.
This approach gives the campaign a miniature character arc and an established beginning and end for a companions journey.
Those who become permanent companions are making a life choice. They are committing themselves to helping the Time Lord in their never-ending battle to thwart the forces of evil.
Such characters are usually adrift when they first meet the Time Lord or looking for a bigger adventure. Their character arc is whether they are satisfied with what they find. Are they content with this life or do they desire something more?
Some characters find a natural reason to leave. Nyssa found a new way she could help people at the Terminus Station while Tegan decided that travelling with the Doctor just wasn’t fun anymore. Leela found love and a new life on Gallifrey.
Others aren’t given the choice. Sarah Jane Smith was abandoned in Croydon when the Doctor left for Gallifrey while Jamie was returned to his own time by the Time Lords.
Exploring what a character wants can be a good way to prevent them from overstaying their welcome. What is that they find most exciting about travelling with the Time Lord? Can these interests be nurtured and eventually give them a reason to strike out on their own?
A companion can mature, changing their relationship with the Time Lord. Amy eventually realised, that she was aging while the Doctor stayed the same. That he no longer held the same importance in her life.
It could be interesting to explore a Time Lord who is oblivious to the aging of a life long companion. Such a companion might join him as a young woman only for her to die decades later, with the Time Lord confused at how the time has slipped away from the them.
If a companion travels with the Time Lord only once a week their relationship will be very different, as will their adventures. Rather than travelling randomly each destination will be special, the Time Lord making the most of their infrequent visits.
Such a setup can allow the companions personal life to be explored. Who is waiting for them at home? How is their career developing? Are their any contemporaneous events that have impacted upon them since they last saw the Time Lord?
This travelling arrangement need not be perfect. It could take a few attempts to get the companion back to their own time, allowing for a few more adventures before their next scheduled meeting.
Rose learnt to her cost that the Doctor can’t always get people back to the moment they left. In her case she lost a year but others might loose much more. What impact would this have on those they left behind and would they risk travelling with the Time Lord again?
The Time Lord might also not turn up when arranged. He might appear a few days or weeks later. Is it a simple mistake or is he having other adventures with other companions? Is he forgetting about those who stay behind? One day he might never return again, either because he has moved on or because something has happened to him.
Not only can player characters cycle through these different travel arrangements but a TARDIS crew can have different mix of these options. One companion could be seeking their lost home world, another has no intention of leaving while a third gets picked up every Thursday to share an adventure.
This can be a good way to handle players who have different levels of commitment. If someone can only play for a short period their character can depart once they’ve reached their destination. A player who can only join infrequently might have their character picked up occasionally while the regular player has a character who is a permanent fixture.
These arrangements can also influence how companions view each other. The full time companion might view the others as part timers or hobbyists. The occasional companion could view the others with jealously or lacking a real life. The one who is trying to get home could view the others as crazy for choosing this life.
By choosing different arrangements a campaign can be made fresh and allow the exploration of different dynamics, both between the companions and the Time Lord.