10 Times Doctor Who Has Broken Its Own Rules

Don't mess around with time. Fixed points. Paradoxes. Don't change anything.

And usually, the Doctor knows when to save people, and when not to. In 2008's The Fires of Pompeii, the Tenth Doctor chose to save a family from Volcano Day - despite their fate being fixed in time. Shortly after, he faced a similar problem.

The Waters of Mars saw the Doctor arrive at Bowie Base One in the middle of a hostile takeover from benevolent, water-based beings. Knowing that the crew were to die in a nuclear explosion in the base - something which would stop the Flood from invading Earth - the Doctor was forced to not intervene. He knew he couldn't save them.

However, declaring that he was in charge of the rules of time and he was "Time Lord Victorious", the Doctor broke his own rules and saved several crew members. However, realising that her death had been a fixed point, Captain Adelaide Brooke took her own life in a bid to set history straight - and remind the Doctor not to meddle with time.

The Ninth Doctor previously established the laws of time as early as 2005's Father's Day, insisting that history shouldn't be messed with. In that episode, companion Rose Tyler didn't follow the rules and broke time - by saving her father.

The Eleventh Doctor, however, had learned his lesson from The Waters of Mars by the time of 2011's The Wedding of River Song. Furious that River Song changed the timeline and destroyed history, he even staged an elaborate fake death to set things right.

It just goes to show that it's better to stick to your rules when it comes to time travel.