Damarchus' origins:
Damarchus was once known as the boy Delios, born in Arcadia, weak and frail, he was heavily abused by his father and brothers for causing the death of their mother, who died of childbirth. Eventually, one of his sibling gave pity, and had Delios flee from his home. Ending up as a runaway, he spent many nights starving and cold, running across Greece until eventually collapsing on practically the doorstep of Knossos. First discovered by a child Asterion, Delios grew an admiration for the young Asterion's gentleness. Minos initially refuses to take in another child, but after realizing that the boy is the son of Arcadia's champion warrior, he realizes he could mold the boy into Crete's own champion. The next few years, Minos tries and fails to train Delios, and realizes that the boy is more adept to training others, after Delios confesses he was secretly training Ariadne to use a weapon. As with Asterion, Delios' admiration for him slowly grew into love, a feeling Delios had little understanding about.
The festival Lykaia was a savage festival celebrated every four years, where human flesh was to be fed to young men for them to transform into savage wolfs, unfortunately at the time, Lykaia fell under the same time as another festival that was to be celebrated in Crete. Asterion pleads to his father to let him go, Minos ultimately obliging but has Phroneos on his literal tail at all times. Ariadne wants to go herself, but is shut down by her father, unlike Asterion, she does not plead him further, giving up quickly. At the festival, a young Scylla gives the opportunity for Delios to be alone with Asterion to go on a date of sorts. Scylla charms and drags off Phroneos to look at jewelry being sold by vendors. While taking a shortcut to an event being held, Delios and Asterion are corned by a peculiar vendor of food, offering them grilled meat after making remarks about the odd duo, while the skewered meat is initially given to Asterion, Asterion rejects it, calling back to when his sisters had him eat beef without his knowledge, seeing his discomfort, a hungry Delios then offers to take it off his hands, which Asterion agrees to.
Unbeknownst to them, the given skewer was of ritual meat for Lykaia, initially given to a targeted Asterion to turn him into a bloodthirsty beast that will allow the Lycaonite werewolves to bring humanity to their knees.
Delios excuses himself, feeling nauseous from the meat. Asterion is then left alone, noting that Phroneos is not in clear sight, Asterion begins to panic with being alone, things only getting worse when patrons of the festival begin to panic themselves from a "monster" ravaging the festival. Asterion, believing they're all referring to him, hides out of his own fear and shame.
Delios, now transformed into a giant wolf begins tearing through the crowd. Ariadne hears this from the palace, and immediately goes to find Asterion, Scylla, and Delios. Ariadne runs off and Minos quickly follows after her. Ariadne, sifting through the crowd, finds Scylla tending to a wounded Phroneos, Scylla and Phroneos do not know where Asterion and Delios are though. The wolf Delios then corners the three, before he can strike, Minos steps in and saves them. Ariadne then notices Delios' birthmark amongst the fur, and deduces the wolf's true identity. Ariadne implores Delios to stop for Asterion's sake, Delios overwhelmed with bloodthirst, is quickly overtaken for his feelings of Asterion, and snaps back into a placid feral state. Delios, with barely any consciousness left, knows Asterion cannot see him in this state, and flees off into the Cretan wilds.
Finding Asterion hidden away in a stall, sobbing to himself, Ariadne is disgusted at her father, claiming none of this would've if he just let her go, and explodes on him after returning to the palace, which ultimately leads to the princess accidentally persecuting Asterion at fault alongside Minos.
Asterion through all of this, was unaware of his friend's Delios' fate, something he never gets to learn up to his death in the Labyrinth.