Giving NPCs memories can go a long way to making a more realistic and enjoyable game world.
This is not a submission about creating NPCs, this is about presenting them. Not everyone walks around with a different accent, strange tic, or catchphrase, our memories are what make us different.
The PCs come across a wild thicket of luscious looking blackberries. They eat the berries and become drunken fools. Later they find out that the berries were part of a fae garden and were intended for fae wine. In payment for stealing the berries, the mischievious fae make life inconvenient for the PCs. Horses are untied, water skins are drained, spare clothing is drug into the water, etc.