Artemis- Initial Atlantis Complex Symptoms

There were more than a dozen tables inside the restaurant, all with
chairs stacked on top, except for one, which had been dressed with a
linen cloth and laden with bottled glacier water and spa bags for each
of the five places.
Five, thought Artemis. A good number. Solid. Predictable. Four
fives are twenty.
Artemis had decided lately that five was his number. Good things
happened when five was in the mix. The logician in him knew that this
was ridiculous, but he couldn’t ignore the fact that the tragedies in his
life had occurred in years not divisible by five: his father had
disappeared and been mutilated, his old friend Commander Julius Root
of the LEP had been murdered by the notorious pixie Opal Koboi, both
in years with no five. He was five feet five inches tall and weighed
fifty-five kilos. If he touched something five times or a multiple of
that, then that thing stayed reliable. A door would remain closed, for
example, or a keepsake would protect that doorway, as it was supposed
to.
Today the signs were good. He was fifteen years old. Three times
five. And his hotel room in Reykjavík had been number forty-five.
Even the Ski-Doo that had got him this far unscathed had a registration
that was a multiple of five, and boasted a fifty cc engine to boot. All
good. There were only four guests coming to the meeting, but
including him that made five. So no need to panic.
A part of Artemis was horrified by his newfound superstition about
numbers.
Get a grip on yourself. You are a Fowl. We do not rely on luck—
abandon these ridiculous obsessions and compulsions.
Artemis clicked the case’s latch to appease the number gods—
twenty times, four fives—and felt his heart slow down.
I will break my habits tomorrow, when this job is done.
...

Holly studied Artemis closely. He was pale, more so than usual, like
a creature of the night. A snow wolf maybe. The sharp cheekbones and
triangular length of his face added to this impression. And perhaps it
was frost, but Holly thought she could see a streak of gray at his
temples.
He seems old. Foaly was right: Artemis looks beaten.
Then there was the number thing. And the touching. Artemis’s
fingers were never still. At first it seemed random, but on a hunch,
Holly counted, and soon the pattern was clear. Fives or multiples of
five.
D’Arvit, she thought. Atlantis Complex.
She ran a quick search on Wicca-pedia and came across a brief
summary:

Atlantis Complex (at-lan-tis kom-pleks) is a psychosis
common among guilt-ridden criminals, first diagnosed by Dr.
E. Dypess of the Atlantis Brainology Clinic. Other symptoms
include obsessive behavior, paranoia, delusions, and in
extreme cases multiple personality disorder. Dr. E. Dypess
is also known for his hit song, “I’m in Two Minds About
You.”

Holly thought that this last bit was possibly Wiccahumor.
Foaly had reached the same conclusion about Artemis, and said as
much in a text message he buzzed over to Holly’s helmet, which sat on
the table before her. Holly tapped her visor to reverse the readout then
read the words.
Our boy is obsessing. Atlantis?
Holly called up a Gnommish keyboard on the visor and typed,
slowly, so as not to attract attention.
Maybe. Fives? She sent the message. Yes, fives. Classic symptom.

- The Atlantis Complex, Chapter 1