While Shirayuki handles fruit that makes a good alcoholic drink, Zen remembers a troubled time in his past.
This flashback was a definite tone shift. Zen becomes friends with a boy his age, Atri, but then he’s betrayed. (Atri’s eyes are scary.)
On the positive side we also see how Zen and Mitsuhide, his attendant, became friends. (Mitsuhide has not aged.)
This story explains a lot. It explains why Zen didn’t trust Shirayuki at first, she had to prove herself. It also explains his older brother’s concern about their friendship.