Where did dragon come from in the Shrek Movie
All of the characters came from a some fairy tale.
Here are the possibles:
All obscure references to dragons in fairy tales are going to be ignored for this question. The tale must be know to children of the time.
Two Disney films:
Pete's Dragon - There are many dragons in this film.
Sleeping Beauty - Maleficent does turn into a dragon.
This film has the back story of a dragon interacting with a small boy. Spoiler: There are many dragon's that show up at the end.
This is a world were dragons are present. A fairy from another world would be able to magic one dragon into her world.
This task would be very easy for the fairy in Shrek. She could use her crystal ball to locate a dragon. All she needs is that one dragon.
The dragon in Shrek is tied to the castle. So, the dragon will never get to escape.
The dragons in Pete's Dragon can talk.
It is possible that the fairy could have made her unable to talk. This would make it so she can never call out for help.
Why didn't the dragon save the Princess?
The dragon is chained down. The dragon might not be able to reach the high tower.
Or, the dragon might be magically unable to help the princess.
Who is to say that this did not happen in the third movie. Shrek was not able to save the princess. Maybe, the dragon decided to save the princess because she didn't want to stay at the castle.
This might have happened so that the dragon could get back to her family.
The dragon in the Sleeping Beauty is Maleficent. There might be other dragons in that world.
But, only one is mentioned.
When would this likely to happen?
Maleficent might have been near death. The fairy of Shrek could have offered her a deal to live.
--Spend a number of years guarding a princess in dragon form. Then, the fairy would release her. the fairy would be able to go home and get her revenge.
The fairy might have taken away the power to speak or use magic. This happens in The Little Mermaid where the princess loses her voice.
She does not seem to know love.
This could change over time. There are many knights wanting to find their love.
They might have confessed their love while they lay dying. This might have made the dragon want to be loved.
Which one would be more likely?
Both. But, Pete's Dragon is a family Disney film where the dragon is not evil. And the dragon is very forgiving.
This dragon is not forgiving in the last Shrek movie. She does try to eat donkey. This is after being abused.
This does lead to Maleficent being the dragon.
None of the dragons in Pete's dragon tried to eat anyone. The dragon never tried to kill anyone.
Why didn't Dragon turn into Maleficent if she was Maleficent?
Maleficent wanted to be loved. Donkey loved her. So, she never used her magic to turn back into a fairy.
True loves kiss
True love's kiss is mentioned in Sleeping Beauty.
True love's kiss is also mentioned in Shrek by the princess.