A dialogue packet is a way of avoiding all those repetitive “he said” and “she said”s that can quickly litter a page. Instead, you structure your paragraph in the following format:

Stimulus – something happens to the character, evident from the text
Internalisation – the character ‘internalises’ the event, perhaps by thinking about it or relating it to a previous event
Response – the character says or does something

For example:

Mark walked into the room and saw his sister leafing through his diary. He felt his whole world collapse around him. For months, he’d had a feeling this had been happening.
“Do you really have to do that, Karen?”

Here, the first sentence is the stimulus, i.e. what Mark sees happening. The next two sentences are the internalisation, which intensify the emotional response to the situation. Finally, the next paragraph gives the dialogue. Note that there was no need to add “Mark said” or “he said” after the dialogue, since it is evident from the context who is speaking. In some cases, internalization can be left out, for example:

A door slammed shut and the sound of footsteps came loud and clear from the hallway. Leah shuddered. “Who’s there?”

Sometimes, internalisation can slow things down, so in action-packed scenes, it’s best to limit it or leave it until the end of the scene or the next scene. I’ll talk more about scene structuring in a later post.