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 find a small green glass bottle, something can be seen writhing within the smoked glass. If the PCs open the bottle a repulsing form of life will pour forth and grow in size. A genderless beings of soft pliable purple flesh towers before the PCs, it has no detail, no distinguishing characteristics except for a narrow slit for a mouth that holds rows of inwardly curving teeth.