Loki the God of Mischief has been growing in popularity over the years in both the Marvel Comics and especially the MCU, considering Loki is receiving his very own TV Series that may already be renewed for a second season on Disney+. The reason for the character's longevity and growing popularity is because of his charisma, antics, camaraderie, and of course mischief. Out of all of Loki's family members, the most prominent figure is his brother Thor the God of Thunder, who he often teams up with and fights to the death.
The second most prominent figure is his adoptive father and the king of Asgard, Odin. Odin has been around in the Marvel Comics as well and recently dies in Thor: Ragnarok. The third-more so in the comics-is Hela the Goddess of Death who makes an appearance in the third Thor film. But because the Marvel Comics and MCU focus mainly on some of Loki's immediate family, few people know he has a half-human son.
In the Marvel Comics, Loki has five children including a horse named Sleipnir, a wolf named the Fenris Wolf, a snake named Jormungand, a son named the Son of Satan, and lastly a half-human son named Vali Halfling. According to the comics, Vali's mother-a mortal-gives birth to him on Earth and Loki brings him to Asgard. Soon after arriving on Asgard, he befriends Siingard, a powerful Frost Giant-who becomes an important asset in his future battles. Because Vali Halfing desires power, after having many children, he trades them for knowledge of immortality with the Troyjan race. But like his father, Vali is capable of as much good as he is evil.
According to the Marvel Comics, he eventually takes the name Agamemnon and creates the Pantheon, which is a think-tank dedicated to improving humanity by eradicating war, famine, and disease. To aid his endeavor, he recruits some of his children who are hybrids-like himself-and exhibit superhuman abilities such as immortality. Though, his endeavor fails when he betrays his children and tries to kill them all. As a result of his betrayal, he dies while trying to escape on a rocket. But like father, like son he cheats death and is resurrected-with the desire to regain control of the Pantheon.
It's surprising Loki's son Vali Halfling doesn't make more of an appearance in the Marvel Comics and or the MCU because there is no doubt he is like his father in every way. A character who is capable of as much light as he is dark, who bears one mission in mind-to only serve himself.