“If you catch any fish before I do, I will KNOW you used magic to cheat.”
“That’s not very fair of you. I might simply be more talented than you—or possessed of a good deal more luck.”
“Or you might manufacture your own luck by using magic to cheat.”
“Yes, well, that is always a possibility.”
“If you boys do not stop bickering and get started, I might just outfish you both.”
(See the whole series at http://archiveofourown.org/works/3204995)