The resulting end to her magical banishment of Christmas allowed Father Christmas to return to Narnia for the first time in a century.
Upon his return, he gave many Narnians (along with Peter, Susan and Lucy) various Christmas gifts. Mr. Fox was one of the fortunate recipients, as he and a party of other Narnians were given a huge Christmas feast.
Unfortunately, as they began to eat, the White Witch happened to find them during her hunt for the Pevensie children. She demanded to be told the meaning of the feast, and where they had gotten it from. Having been told it was a gift, she further demanded to know who had given it to them.
Mr. Fox was terrified of the witch, but seeing no other choice he told her the truth; that Father Christmas had given it to them. Jadis did not take his answer well.
She insisted that he had to be lying, even going so far as to offer him mercy if he confessed. Unfortunately, one of the other Narnians present, a very young squirrel, cried out that it had indeed been Father Christmas, and the witch in her rage used her wand to turn all of them into stone.
Unintentionally, Mr. Fox and his companions had a great influence on the character of their future King Edmund, who witnessed the incident. They were the first people who Edmund had pitied (besides himself) since before he went to live at Professor Digory Kirke's House.
The rest of Mr. Fox's history is unknown, except that he and the rest of the party were brought back to life by Aslan after the fall of the witch (as recorded by one of C.S. Lewis's letters).
Mr. Fox was a relatively old Fox (the oldest one of the party), and when he speaks he is obviously very fearful of the White Witch, though he was brave enough to be the first one to speak to her when she arrived.
- "Please, your Majesty, we were given them. And if I might make so bold as to drink your Majesty's very good health--"
- ―Mr. Fox (Chapter 11) [src]
He soon lost whatever bravery he had, though, when the witch demanded to know who had given them the food, no doubt guessing what her reaction would be.
- "Who gave them to you?"
- ―The White Witch and Mr. Fox (Chapter 11) [src]
In the 2005 film, Mr. Fox's role (voiced by Rupert Everett) was dramatically extended and altered. At the start of the Winter Revolution, he was charged by Aslan to go around Narnia, to find and enlist anyone who would fight in his army. While searching, he came upon a group of Narnians turned to stone, who had been helping the Faun Tumnus. Unfortunately, the White Witch had discovered this and had arrived there before the fox did, and turned them all to stone before he could help them.
The fox did, however, arrive there just as the beavers and the Pevensies arrived, and helped them escape the Secret Police by telling Maugrim and his wolves that they had run north, despite nearly getting mauled by them, which gave the five travelers more time to travel to Beruna.
While they did this, the fox travelled around the woods to gather more creatures to fight in Aslan's Army. He was later found by some wolves in the Shuddering Wood, where he was still gathering troops to send to Beruna.
The wolves captured him and brought him forth before the White Witch, but he refused to tell her anything about the Pevensies or Aslan.
When the fox did this, the Witch was about to turn him into stone, only for Edmund, trying to save his life, to end up telling her that his siblings were on their way to the Stone Table, and Aslan was building an army there.
When Edmund did this, the fox had looked at him in sad pity, no doubt in despair that he had given the Witch what she wanted, and also perhaps knowing what was about to happen, just before the Witch turned the poor animal into stone anyway.
(Any Narnian would undoubtedly know what the Witch was like, and knew she was not to be trusted. So the fox would know that once she had what she wanted, his life was forfeit.)
Fortunately, the fox was resurrected by Aslan's healing breath, and was most likely part of the reinforcements who helped turn the tide of the First Battle of Beruna.
He was later seen at the Pevensies' coronation, where they became the new monarchs of Narnia, standing next to a lioness. (The lion's face had a comical moustache and glasses drawn upon it, which had been done by Edmund, while the lion had been stone, when he had visited the Witch's castle.)
In the Disney movie, Mr. Fox's character is altered exceedingly. For one thing, he is clearly not an old fox, as made evident by the way Aslan charges him to go around Narnia, finding new soldiers for his army. He is also a lot braver than his book counterpart, seen by the way he faces up to the White Witch and her wolves, refusing to tell either of them anything, even going so far as to insult her by addressing Edmund as "Majesty" instead of her.
- "Forgive me, Your Majesty."
"Oh, don't waste my time with flattery."
"Not to seem rude, but I wasn't actually talking to you."
- ―Mr. Fox and Jadis [src]
He has a very quirky personality, with a hint of trickiness, bravery, and he is shown to be clearly devoted to Aslan and the Pevensies, and fighting for Narnia's freedom.
- In 1953, C.S. Lewis received a letter from a distressed child, asking him about what happened to Mr. Fox and the party of animals after they were turned to stone. He wrote back to the child, re-assuring her that the animals were indeed brought back to life.