Suspense v Surprise

Suspense is when we think we know what will happen and are waiting.

Surprise is when something happens we didn't know was coming. 

Suspense is of little interest to a reader (in our trade) without malevolence. In the illustration here, there is a loaded firebox and in the second frame a fire. Hardly suspenseful. 

If we the reader know that a log is hollowed out by our murderer and filled with 2 lbs of black powder, well.  We have suspense. We think we know the log will explode and with it the stove. Will it kill/harm/maim our victim? Will they cleverly wander to the kitchen and defeat the evil intentions of the murderous brother-in-law ? 

Suspense and surprise work well together.

We show the pistol in the drawer of her writing desk.

We know the rounds are duds having had the powder removed by the intended victim anticipating their possible use.

We see the contrived argument.

We see the pistol being retrieved from the next room's writing desk.

We see it brandished.

We wonder, will the trigger be pulled and if so what are the consequences ?

The gun is fired. A body falls.

Shock. Surprise - both on the face of the victim and on ours as the reader.

Now what ? 

Do you reveal that the murderer has two identical pistols and used the one she retrieved in her purse ? 

Do you have a clever killer who replaced the bullets suspecting they were altered ?

Do you have in incompetent victim who altered bullets - but not all of them ? 

How do you handle it? You have a great scene. You have a mystery - not the ones your cops will have to solve but one your reader needs resolved. 

What do you do ? 

The suspense is foreknowledge of some unfortunate happenstance. The surprise is the twist, the unforeseen.

Neither can exist in a fashion to cheat the reader. Perhaps the murderer reveals that she had contemplated suicide and so used the pistol on herself earlier in the morning. To her horror, it didn't fire. She tried several bullets and none worked. Then, she became furious. She knew the victim had access to the weapon. The murderer was angry that the victim would think her capable of using the gun for murder. In attempting to prevent a shooting, the victim had pushed the murderer past where she might not otherwise have gone. She grabbed the gun because this argument brought to mind the manipulation of the victim. He had used his superior intellect over and over to belittle and befuddle her. She wasn't taking it anymore. She had re-loaded the gun (because what use is an empty pistol ?) and when confronted one more time ran to use it and so ... end the game of cat and mouse the victim had been playing for months.

Now, the joke is that her mental state is awkward. She's not in her right mind. After all, she'd tried suicide and now had a murder erupt from a simple argument. It wasn't murder in the first. It was simple homicide and she - in her disturbed state - was hardly in a position to know right from wrong. Any jury would see that.

Wouldn't they ?