Use the phrase "with one look" in your fic. It can be buried deep, or the theme of the fic.
Examples: "With one look, I knew things were never going to be the same again."
"We fell in love with one look."
"With one look I could see that the building was about to fall down."
What happens with the power of one look? The phrase must remain in tact.
90 minutes to look this one over.
Second Challenge: Claustrophobia
The second challenge revolves around the theme of claustrophobia and/or entrapment. You can do this emotionally or physically: ex., Hikaru being stuck in a broom closet with a claustrophobic Akira, being trapped in a mall "Dawn of the Dead" style, the feeling of being trapped, etc. It's a pretty broad challenge, so interpret this as you will.
You have 60 minutes.