If Lannian had survived childbirth, Legolas would have grown up loved and cherished, with a warm and supportive father, a caring mother.
Lannian died due to complications in the birth. Legolas survived.
And from the moment of Lannian's final breath, Thranduil hated the child who had killed his wife.
A human being can go for three minutes without air, three days without water, three weeks without food, and three years without love. An Elf can go for ten times that long.
At the age of thirty years, two months, and nine days, Legolas son of Thranduil faded from the world, starved to death from lack of love. Human eyes would have thought him four years old.
The people of Mirkwood mourned. Thranduil did not.