Furio

The Furio was a fire-based creature which fed on negative emotions such as hate, fear, anger and guilt. When her species came across negative emotions, they devoured its source, thereby "remov[ing]" and "cleansing" it.

Biography
The Furio was unknown to the Doctor, prior to his sixth incarnation. The species did not appear anywhere in the Time Lords' collective knowledge.

On 1 January 1944, the Furio was attracted to Earth by the ongoing Second World War. She landed in France and was found by a member of the French Resistance named Lucien. Lucien himself was full of hate for the Nazis and the Vichy government. These emotions created a psychic link between the two. The Furio folded herself down a thousand times over and resided inside Lucien's cigarette lighter. Lucien frequently summoned her to fight against the Germans. She looked to Lucien as if he were a father.

On 4 July, the Furio burned down a forest near Rouen to flush out hiding German soldiers. On 5 July, she brought down a Messerschmitt, totally consuming the pilot. On 6 July, Lucien summoned her to kill a woman named Clementine for collaborating with the Germans but the Sixth Doctor, Constance Clarke and Flip Jackson stopped her. Lucien accused the travellers of being collaborators and unleashed the Furio to kill them. However, to divert her, the Doctor told her of the hatred coursing through Berlin, the heart of the Nazi regime. This appealed to the hungry Furio enough for her to gain some autonomy beyond Lucien's control, like a rebellious teenager.

The Furio followed a British convoy en route to Berlin but was distracted when the Doctor gave chase and thought about memories producing positive emotions, giving her "indigestion" and making her feel "queasy". Lucien was convinced to let go of his hate and release the Furio like a parent telling a teenage child to leave home. The Doctor then offered a new home full of hate to feed on, telling her of Skaro and the Daleks, although warned her she wouldn't like to feast on any visiting Thals. The Furio departed for Skaro, Lucien noting that she she didn't say goodbye. (AUDIO: Scorched Earth)

Behind the scenes

 * Colin Baker referred to the Furio as "". (BFX: Scorched Earth)