What if shrek never managed to rescue Fiona at that castle?

The whole point to shrek 2 was that you discovered that Prince Charming was actually the one who was supposed to rescue Fiona from the castle. So basically Shrek would have been stuck with Donkey (who wouldn't have met the dragon) and living not so happily ever after. Prince Charming would have found Fiona...and Fiona would have lived not so happily ever after with him.

Actually Shrek was at the castle to rescue Fiona for Lord Farquaad, he was to scared to do it himself, so Shrek really had no intentions on falling in love with Fiona. I think once he realized that Fiona was no shrinking violet but a strong spirit he fell in love with her, also it helped that she really was an ogre by night, Prince Charming as we realized in the 2 Shrek was self obnoxious idioum and was only after the kingdom of Far Far Away, so you see if Fiona had married Prince Charming it would have only been a marriage of convenience and the ogre curse would be gone, she would have her beauty but no happiness, something like Princess Diana amd Prince Charles marriage was like and we all know how that one ended.