Heart.

A thin bright red trail followed Allen Walker with every step that he took, the color dyeing the snow.

On Allen's left wrist was a heart; human of course, and still beating at a normal rhythmic pace.

Next to Allen was Tyki Mikk, who had a teasing smile on his face and snow in his chin-length hair. Unnoticeable to Tyki, Allen, and the human eye in general, there was a large red stain on Tyki's white shirt.

Allen let out a laugh and the heart on his wrist started to bear a little faster while Tyki's lips twitched slightly upward.

On Tyki's wrist, there too was a heart. It wasn't as red or as large as the one of Allen's wrist, but it was still there, regardless. It was still growing day by day, after all. A few drops of blood fell on the snow covered ground, lightly dyeing the whiteness, that was much like the soon-to-be past owner of the heart.

Because, well, they weren't technically the owners of their own hearts anymore.

Or, at least, Tyki hadn't been the rightful owner of his since he had first laid eyes on a one Allen Walker.

And, soon enough, Allen wouldn't own his anymore either.