Mild spoilers for puzzles

I'm stuck in the red room, as I'm only able to figure out the lower left paintings. Here's all I know:

• The upper left paintings involve the words "run" and "fun". I figured this one out!
• One of the upper right paintings may involve the word "safe".  Actually, I think both paintings involve the words "rock" and "lock"!
• The lower right paintings involve the words "clown" and "down". The painting on the right is pointing down to some bloody footprints.

Some things to chew on:

Top right:
- What's the theme of these eight puzzles?
- What's behind the door?
- Heck, what's behind the door in front of you?
- What's underneath the boulder?

Bottom right:
- What is it called when someone or something is expected to have arrived already?
- Who might be interested in such footprints, and what might it represent to them?

And as always, a good starting point is using the letters/sounds from one phrase in the other.