How casting can change a scene

 Consider the following installation. 

By itself, it could be almost anything. Maybe slightly ominous, depending on what the music is like.

Now let's add a character. Maybe a nice old lady astrophysicist .

Suddenly, it is probably just some funky radio telescope or similar. Perfectly normal, nothing bad is going to happen to anyone because of it.

So let's change it to some bloke scientist.

Everything is still probably fine, depending on the music. Just some researcher. This does not mean that things might not go horribly wrong, but they seem to be perfectly normal.

We can make it even more normal by using two characters -

Honey! I'm home! But I digress. Back to the slow decline.

Now things are looking dodgy. Red glasses, self-satisfied smirk, weird flask of something green... it all adds up to this is probably nothing good for anyone. But we can step it up more.

OK, exposed brain alien dude. Let's face it, we're in for a rough and nasty ride. Probably with some awful acting. Or are we?

Honey! I'm home! I've brought drinks! Suddenly everything is OK, if a little odd. But who are we to judge?

And now it could go either way. Mad scientist, or bohemian? Has he brought a cocktail or a world-ending virus? 

This, however, is almost certainly bad.

And lastly

There is no way there is anything good happening here. 

Of course there are other directions for all of this. Consider

About which little needs to be said.