Being alone is never easy.
No matter how used to being alone you are, it doesn't ease the pain. It's like a constant grinding on your soul, and you wait for yourself to go numb but the nerves just never die.
For Jack Frost, it was no different. If anything, it was worse.
250 years before, he had awoken in the lake.
Everyone he'd seen that day had not seen him. Everyone he'd tried to greet walked right through him. No one heard his voice. No one had even suspected he was there.
Jack's first year as the spirit of winter was spent in wild desperation. After the unpleasant realization in the town by his lake, he flew around the globe, talking to everyone he saw, hoping that someone would see him.
No one did.
The next was spent in depression. The worst feeling is knowing that even though there are people all around you, you are completely alone. No one knows that you're suffering, and no one even cares.
Jack moved around constantly, riding the winds to different places around the globe, unable to stand being in one place for too long. Jack never laughed. He never even smiled. He ached so much it was all he could do to keep moving about. He brought cold and snow like he was meant to, but there was no soul behind it.
Jack was empty.
But eventually Jack decided that being depressed as he was did no good to himself. It was boring and a waste of time. He wanted to be happy. He wanted to cause mischief. And so he did. He shoved his depression into the back of his mind and began his new life, as a being of fun. So, for two hundred fifty years, he rode the winds, created snowstorms, painted windows with his beautiful frost, built snowmen in the night, and tossed a few snowballs to the unsuspecting kids who would turn and see...nothing.
But you can only fake being happy for so long. That depression in Jack swelled behind the wall he'd put up, just waiting to come back out.