Draco Dei
Both of them have significant stresses in their lives, and periodic bouts could explain Spike's lack of growth. However I can't quite make it jive in my mind, because Spike seems to be entirely too good at chilling out(a) to have an anxiety disorder. Are my perceptions off?
(a)And getting Twilight to do so, but that could be argued to be a case of being better at helping others than you are at helping yourself.
Scootaloo... yeah, that could fit like a glove "I could fly if I weren't such a tub of lard!". *Proceeds to lose more muscle mass.*
EDIT: If you did Spike, he could use the excuse "Gems are expensive. I don't want to be a burden on the royal coffers.". I still have trouble making it fit with his personality.
(a)And getting Twilight to do so, but that could be argued to be a case of being better at helping others than you are at helping yourself.
Scootaloo... yeah, that could fit like a glove "I could fly if I weren't such a tub of lard!". *Proceeds to lose more muscle mass.*
EDIT: If you did Spike, he could use the excuse "Gems are expensive. I don't want to be a burden on the royal coffers.". I still have trouble making it fit with his personality.