He wonder how the others do it find that one person who they trust with every bit of themselves. He has seen it in all the shows they've performed at there is always a two souls straining to be near.
Weather they are romantic or platonic their souls always shine brighter. As though trying to escape their shell to finally reach one another. Souls prevented from joining by walls of flesh and bone. At times the feeling of anger and hatred would crash a pin realizing that he might never meet his half.
His own soul was impossible to see but Mabel assured him it was the darkest black.
The same could be said for hers it was the darkest black he had ever seen. He saw as it as it strained and moved reaching out he could never tell where to though. As the magic poisoned their souls and made them sluggish unlike those pure of heart. Yet it still glittered sluggishly when she was happy. Giving it a beautiful mysterious quality that he loved to see.
Not to say all souls shined brightly but those of soul pairs and those pure of heart always did. So he always did enjoy making it shine. As it did fleetly like a shooting star in the night sky.
So when the opportunity to make her happy came he gladly took it.
So when he saw the Pines boy with the third book in his hands as he snuck around the tent of telepathy. He just know he was going to have the a chance to see his sisters soul shine.
After all nothing made her shine more than causing pain and destruction.