Problem: Continue the following story.

Aaron's relatives come from Germany, while Adam's come from Japan, so 
Here's how I want to continue it: Aaron is of European descent.

Problem: Continue the following story.

Brian asked Adam to do all that he could to increase his engine's horsepower. 
Here's how I want to continue it: Adam was his mechanic.

Problem: Continue the following story.

The windows were very dirty, but Joseph saw no reason to clean them while William immediately cleaned them.  
Here's how I want to continue it:
Joseph was a naturally dirty person.