[@Diexsmiling]
[sub]the numbers i got were calculated
but man
am i bad at math

Anyways, luck ‘n’ stuff.
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Let’s assume that a person’s luck can be represented by a line on a wave graph; above the center is good luck, below is bad luck. Whenever someone’s luck increases above the norm, there will be a “rebound” that pulls their luck down by an equal amount before returning to normal, and vice-versa.

The way a wish works is by forcibly pushing up a person’s present fortune enough to grant the wish(asking for material wealth or something that doesn’t exist is much more costly; the material would have to come from somewhere, and EXTREMELY specific conditions would have to occur for something new to be created). Thus, at some point in the future, their luck will decrease equal to the amount of fortune they used up.

Because of Astrophel’s (un)natural tendency towards misfortune, he is unable to increase his luck unless he decreases it first. Therefore, if he makes a wish to stay safe during a dangerous situation, the events follow this order:

His luck decreases to even lower than before, practically guaranteeing that another unfortunate event is going to affect him => his luck increases, causing the second event to turn in his favor(albeit still possibly dangerous for him) => the two events cancel each other out, returning his luck to normal.
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While wish demons do have the ability to both increase and decrease luck, there are two reasons that they generally only increase it:

Firstly, decreasing a person’s luck requires more energy, which they get from feeding on misfortune, than increasing it. Unless the wish demon is altruistic(not a trait that demons normally have), they have no reason to do so.

Secondly, they are only able to manipulate the luck of a willing being; the only people that enter a contracts with wish demons are either greedy or foolish, generally both. Since those people are looking for quick gains, the demons are really only ever given the opportunity to increase luck.

Partially because Astrophel’s perpetually bad luck cancels out those two reasons(unlimited misfortune, making him unlucky actually protects him A.K.A. the unlimited buffet) and partially because he’s actually happy about being his friend(despite what he says), Aery stays with Astra.
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... I should really stop going so deep with these concept-type things[/sub]