Here's how:
* Their behavior is described as odd and secretive. They are portrayed as being "shifty," "nervous," and "afraid." This makes the reader question their motives and creates a sense of mystery around the household.
* They seem to know more than they let on. The servants are aware of Jekyll's strange behavior and Hyde's existence, but they don't reveal this information easily. This suggests that they are keeping secrets, possibly out of fear or some kind of loyalty to Jekyll.
* Their appearance is often described as unsettling. The servants are described as "gaunt," "shady," and "sullen." This adds to the overall atmosphere of mystery and unease that surrounds the story.
The servants, therefore, act as a kind of foreshadowing to the darker, more sinister elements of the story. They hint at the hidden secrets and the dangers that lurk beneath the surface of the seemingly respectable Dr. Jekyll.
In essence, the servants reflect the moral ambiguity of the novel, where even the seemingly innocent can hold secrets and be complicit in something darker.