ye olden boy

this is princess luna's oldest kiddo, palest cosmos
his dad is king sombra, but no one other than himself and luna know
luna was the only one to find remains of king sombra in the outskirts of the crystal empire. the chip of his unicorn horn still had part of his magic attached to it, and it infected luna. she became terribly ill, with sombra attempting to corrupt her dream abilities and escape out of the dream world to reality. but sombra was unlike the tantabus, and he could not destroyed. she cautiously released him from the dream world. sombra was much more weak now, almost devoid of his power, which had absorbed into luna. she decided to nurse him to health, in hopes of reforming him. then there was the night it happened.
sombra was in full power, and betrayed luna. she had no other choice than to kill him, which didnt happen without grief. the remaining essence of sombra inside luna spread in her own dna, and eventually caused her to become pregnant. lemme tell you that luna was freaking the f out when she found out
but she felt she should keep the baby, which was palest cosmos