Seeing Anastasia for the first time since her death two years ago made Zen feel like turning back to his usual fragile form - to the days he was unknowingly depending on her more than he thought he was.
In other words, he feels like a child again all of the sudden. At the outbreak of all the rioting emotions that he worked hard to bottle up before, he forgot everything he became to be ever since he lost her. He forgot about being an officially renowned scientist, being one of the top soldiers in the military, and being the outstanding young man that he had grown to be.
At that very moment, Zen is back to being that weak and vulnerable Lucien.
"Anastasia... I-I'm so glad... I'm so, so glad..." he murmured in between sobs as he continued to cry in front of her.
Ever so gently, he cups her pale cheeks with both of his hands. Despite his blurry vision, he keeps staring at her as if she is his entire universe. He looks at her as if she is his home.