Grammar
It hadn't been difficult to hack the system. Now that it was fixed he felt as if a weight had been lifted off his chest. Just looking at it had made him tense.
Fowl was spelled with a capital F. Anything else was bad grammar, and he hated bad grammar.
This is just a really random half drabble inspired by the fact that finally changed the category name from Artemis fowl to Artemis Fowl. The lowercase 'F' always bothered me.