Jack hadn't really been feeling like himself ever since Elsa had left. He knew he was supposed to care about his classes, and about keeping a job, but the truth was he didn't. When he became a Guardian, it was the first time he could remember that he'd ever felt like he had a purpose, like he actually mattered. Like his life meant something. Here, he didn't have that.
And then he'd met Elsa, and things started looking up again. He didn't feel that alone. How could he be alone when there was someone else like him there? Without her around, Jack wasn't sure who or what he was supposed to be now.
Whenever he felt like this, the only thing he felt like doing was make someone else's day a little brighter - and that tended to involve his powers. It grounded him, using his powers that way, and reminded him of his purpose. He was careful not to cause too much trouble, since not everyone seemed to appreciate deeply snowy hallways or frost-covered plants in the middle of September, but no one minded a little light snowfall that melted before it hit the ground, right?
He rounded the corner and stopped when he saw a girl there too. The tower was usually pretty empty at this time of day, so Jack hadn't expected to see anyone. The snow stopped right where Jack was, hovering in the air. "Hey."