Enchanting

[Ellisone]

What the heck do the blue and purple sprites do?

[Sir Stardust]

The Indigo Sprites' enchantment helps you raise friendship with people more quickly. The light Blue Sprites work at Regis's mansion, and help to decrease the amount of lava in the mines. The Purple Sprites work at Lanna's house, and increase the amount of bites you get while using a fishing rod.

[Veggie Angel]

The only thing I can add to what Sir Stardust said is that the purple sprites will be at Lanna's or Denny's depending on whether you are playing as a female or a male (Lanna's if you are female, Denny's if you are male). They increase the number of objects you will land no matter which location they are walking around in.