He, of all people, knew it was wrong.

He, of all people, should not show his emotions.

And of all the people to fall for, it just had to be Lenalee.

He didn't know when it'd started. Probably a long time ago, only that he had never realised it. Lavi remembers the time when they were on that ship to Edo. What he remembers most clearly isn't of how devastating the Level 3 Akuma was at the time, but of how Lenalee left the ship alone to deal with that Akuma in question. He remembers how she hadn't returned to the ship even though they had fought off most of the Akuma; and he remembers how the regret that he'd left her alone at that time tore his heart into pieces.

That joy he felt when he found out she was safe was almost like a sin.

Lavi collapses in one of the armchairs in the Order's library and thinks. He wonders when it had all started; he wonders how he fell for her. Perhaps it was the way Lenalee smiled at him every time. Perhaps it was how she always cared about the people around her. Perhaps it was how she'd risk her life for all of her friends.

He didn't get how, or when, or why. He doesn't know how he falls for her. He doesn't know when he fell for her. And most of all, Lavi doesn't know how Lenalee manages to melt his heart with just a simple smile.

To Lavi, his heart is non-existent. It only serves to keep him alive. Feelings and emotions? Those he didn't care.
His heart was like a stone, in essence. Laiv would never wear his heart on his sleeve-- that was what his head was for. That was the mark of a true Bookman.

And yet Lenalee managed to strip all that away with just a simple smile. Why, really?

The answer was simple.

He loved her.