Sihwa

A half-human alien who wanted revenge on his father came to Earth, but found his lover and his father's diary there. His mother, who also came to Earth to retrieve the diary, revealed that his father had died long ago and she simply wanted to create a copy of him, but Sihwa didn't look much like him. Scientist Sasha (Sihwa's adoptive brother) considered disposing of him at his mother's request, but the earthling insisted that he deserved a full life and couldn't be disposed of just because he didn't look like his parent. Sihwa took the earthling (and his landlord + friend + Sasha's lover) with him to Alpha, his home planet, to explore space.