1) Aliens being extremely confused when humans that spend any length of time in the area with the nice fashionable wallpaper become nauseous and when questioned try to explain that the patterns are moving
2) True Facts(TM) about Ghosts -- Anon Guest
[AN: This puts the gap count down to three!]
The Klypt'l had done their best to be accommodating. They had refurbished any and all human artefacts into useful furniture -even comfortable furniture- for the use of their Deathworlder guests. They had even decorated the walls with an interesting pattern of circles and lines in the bright colours they enjoyed.
All in a sincere effort to woo the humans into helping them with their trade routes.
The humans came, of course. They were the kind of species who never turned down a party. Free food, music, and entertainment were always welcome. They played as hard as they fought... and they were unstoppable fighters.
They did not come in the indomitable battle armour. Outside of their protective shells, they looked deceptively soft. But this was a species that could bite through their own fingers. They could leap higher than their own bodies. They were, in essence, legendary.
They were amused by their accommodations. The Klypt'l in charge of the events took heart at this. Happy humans were good news.
Disaster unfolded inside of two Standard Days, when the humans began to feel nauseated.
Klypt'l Associate K'kreet attempted to understand.
"...the wallpaper," said one of the humans. They were pale and perspiring. Swallowing drool lest they regurgitate their last meal. "It's moving... makin' us seasick..."
K'kreet looked, but the wall decoration pattern remained solidly where it was. It was not moving at all. She attempted to make this clear, but the humans insisted that it was moving and the motion was a nauseating one.
The Klypt'l hurriedly took the humans on a greenscape tour whilst the Comfort Advisory Committee quickly over-painted the walls a nice, safe grey.
Of all the things that humans believe in, ghosts are the most problematic. Even those who do not believe in ghosts know better than to mess around with potential ones.
Never give an open invitation in an abandoned space. Never ask if an unseen someone would like to play. And never, ever, ever make them angry.
Things that make even the deadliest humans nervous are empty structures. Especially empty structures that seem like they were once live-able. There, the most well-known Deathworlders speak in hushed voices and flinch at the slightest sounds. They apologise to any spirit still present. They pray to their god or gods where appropriate.
They tread softly.
And, on more than one occasion, they have been right.
Residual Life Energy has been measured. The place has to be old, it has to have a lot of history, and it has to have strong events associated with it. The living give the phenomenon a personality.
Belief shapes all following events.
And some humans, those who are born Espers, can manipulate RLE and shape it to their will.
There has yet to be conclusive evidence of heavens or hells.
...which means that the assembled Galactic Alliance is starting to get very nervous about 'elves' and 'faeries'.