The summer was hard on Yukidaramon's frozen body, and he hated the thing made her so weak. After she died, he felt like a traitor every time the first mild winds announced the coming of spring – because every time, he failed to deny the elation washing over him as his bones thawed.
Ikuto's not dumb; he recognizes what Sayuri is the moment she gives him food. He doesn't know how a mother gets a child, but understands that the child she gets at least must be somewhat like her – he can see traces of her face in Masaru's, in Chika's.
He knows that Yukidaramon found him when he was very little, and now, he knows that he was somebody else's first. He has stopped flinching at the boy in the glass, and that may be why he can't – no, won't – push the woman away.
He still doesn't know what a father is.
It isn't long until Ikuto will know what a mammal is, and how humans grow without evolving. He will know about C++ and assembly language and digital data; he will have to. Ikuto will not forget the day Gotsumon taught him that a digimon can crush his heart as easily as any human, and Masaru taught him that friendship doesn't ask who your mother was.
He will know why he bleeds, what the drum in his chest is.
Ikuto will understand why he is warm when Yukidaramon was cold, but he will never forget how she died - in fire.