Loki was the son of Fárbauti, a jötunn (giant), and Laufey, a lesser known female god. His mischevious nature was such that he even managed to slither his way into becoming one of the Norse deities, and Loki was known to be a god of fire as well. His jötunn heritage does aid in explaining the complexity of his character, as the jötunns once went to war against the Aesir and are considered, in many ways, their enemies.
Loki, as the son of a giant as well as a goddess, straddles the two warring factions, a trait which plagues his character throughout his mythology. He marries the minor goddess Sigyn, but has many affairs, his most notable with the giantess Angrboða, by whom he gives birth to Hel, the queen of Niflheim; Fenrir, the oversized wolf who is fated to kill Odin at Ragnarök; and Jormungandr, the World Serpent banished to the seas.
The trickster god also, interestingly enough, is the mother of Odin's great eight-legged steed Sleipnir, as Loki mated with a powerful male stallion while disguised as a mare. As his parentage and his progeny are all outside the normal state of affairs even in the godly world, scholars believe that there must have been pertinence to his connection to so many dark and powerful figures in the Norse pantheon.
In the tales, Loki is portrayed as a scheming coward who cares only for shallow pleasures and self-preservation. He is known to be playful, malicious, and helpful, but in the end is always irreverent and nihilistic. Although, Loki can also be quite useful and is appointed or sought out as aid when it came to matters that even the gods cannot handle. While he helps them with his clever plans, he sometimes causes embarrassment and difficulty for them and himself.
He also appeared as the enemy of the gods, entering their banquet uninvited and demanding their drink. However, Loki is capable of showing other emotions, most surprising of which is compassion. For he has showed such a thing towards his children, most notably his daughter Hel. Loki has even managed to form a close companionship with the thunder god, Thor. This is evident in where Loki accompanies Thor on his adventures, sharing meals, and even aiding each other through situations that one of them can solve whilst the other cannot. Although they constantly frustrate one another, they enjoy each other's company.
His tricks came to an end after causing the death of Baldr. Loki is eventually bound by the gods with the entrails of one of his sons. A serpent drips venom from above him that his wife Sigyn collects into a bowl. However, Sigyn must empty the bowl when it is full, and the venom that drips in the mean time causes Loki to writhe in pain, thereby causing earthquakes. With the onset of Ragnarök, Loki is foretold to slip free from his bonds and to fight against the gods among the forces of the jötnar, at which time he will encounter the god Heimdallr and the two will slay each other.