Erasmus is an Akielon slave who was being trained for Prince Damianos before Damianos was supposedly killed. He is one of two dozen palace slaves who are sent to Vere at the beginning of Captive Prince.
Erasmus has light brown curls with a hint of gold. His skin is fair and his eyes are hazel. Damen guesses him to be eighteen or nineteen years old.
According to Aden and his trainers he is exceptionally and naturally beautiful.
He used to have tanned skins in his boy years, but had to avoid sunlight to achieve a fairer complexion, which Damen favors.
Erasmus speaks only Akielon, with "a little skill with Patran and the northern dialects." He tells Damen that he has learned a few words of Veretian since his arrival, specifically: Silence. Kneel down. Don’t move.
In Akielos, he was being trained as a slave specifically for Prince Damianos and looked forward to it. He becomes deeply fond of and attracted to another slave, Kallias, although they must refrain from even kissing.
He is naturally submissive, which is why he likes training as a slave palace and submitting to his masters. As he tells Damen himself, he needs to belong to someone, and could not be as defiant as him. He thinks Laurent is kind, especially since he helped Damianos transfer his ownership from the Regent to Torveld of Patras.
He can play the kithara and has a lovely singing voice. 
The Training of Erasmus
Prior to the event of The Training of Erasmus, Erasmus lived in Nereus' Gardens, eagerly awaiting the day his body would "blossom" and show he is ready to start training as a Palace slave. Three years after his closest friend Kallias left, Erasmus stains his sheets and thus finally starts his own training at the Palace. There, he reunites with Kallias and they both immediately resume their close relationship, although they are not allowed to kiss.
Due to his beauty and fair coloring (cultivated with camomille oil and avoiding sunlight), he is chosen to train for Damen's household after Iphegin's fall, which scars the latter, now unfit to become a royal slave. He gains a gold lion-shaped pin, contrasting Kallias' plain gold one. Aden seems to dislike him for his good looks (an accident of nature which does not warrant praise, according to him) and fair coloring which allowed Erasmus to be a candidate for Damen's service, while his own dark hair only makes him worthy of the sick King Theomedes' bed, despite his own outstanding skills.
During his time in training silks, Erasmus is very dedicated to his education and even enjoys how the harsh summer heat makes it that much harder for him to practice complete submissiveness. The fact that he isn't allowed to touch himself especially tries and excites him, as he fantasizes about being taken by Damen on his First Night after denying himself pleasure his whole life. One particularly challenging night, he wonders if the Prince will bed him like does the strong soldiers he usually favors. Doing so he thinks about a line from an Akielon love poem: "Arsaces, undone", a genre he finds much easier to learn than the long war poems he knows Damen prefers. Indeed, due to his training, Erasmus knows everything about Damen's tastes in food, music, etc. His determination is partly due to the fact that he promised Kallias they would both meet again in the Palace as royal pleasure slaves.
This promise hints to the attraction Erasmus feels towards Kallias, likely reciprocated, its expression only halted by the strict rules training slaves must abide by. They almost cross the line and kiss before Kallias' First Night: overcome with emotion at the prospect of losing his closest friend once again, Erasmus leaves the party to see the sea. When Kallias comes to find him, Erasmus confesses that he is scared he will never get to see the world before his own First Night, which prompts Kallias to tell him he wishes he could have his first time with Erasmus instead. They inch closer, but Kallias stops them just in time.
After Kallias leaves, Erasmus is told his friend has become Kastor's favorite slave, which encourages him to work harder to keep his promises.
As Kastor prepares to imprison Damen and slaughter all members of his household, Kallias comes to see his friend in the middle of the night, claiming he was sent by Kastor. He saves Erasmus' life by deliberately sullying him with a kiss, to Erasmus' great dismay. Erasmus does not understand what has happened and why , and he's unable to defend himself as Kallias accuses him of initiating the kiss, claiming he confessed his love to him, with Aden as a witness. His friend cryptically explains his gesture, reminding him Erasmus told him he wished he could cross the sea.
Erasmus is kept in isolated chambers for 3 days before he is given his slave silks and gold collar 2 years early, when he should have been thrown out of the castle instead. He is among the slaves (12 men and 12 women) sent to Vere, and he seems to dully understand Kallias knew what would happen.
The Captive Prince
Because Veretians do not value the submissiveness Akelian slaves have been trained for, they test their obedience in cruel games. Thus, Erasmus is punished when he fails to contains his screams as he is branded with red-hot iron.
After recognizing Damen as a fellow Akelion, he tells him his story and is charmed by his thirst for freedom, although he reminds him that being a slave himself, there is nothing much he could do to help the Akelion slaves. His submissive nature expresses itself when he shyly offers himself to Damen after the latter praises his fair coloring. However, when Govart notices the fondness Damen has for him in the gardens, he takes him away and it is heavily implied he raped him and took his virginity, which Erasmus had painstakingly preserved until then. This event forces Damen to fully realize his helplessness in the Court of Vere.
After Damen makes a deal with Laurent to save the Akelion slaves, Erasmus is warned by the latter that he will have to endure brief suffering to reach freedom. Thus, he is forced to sit still as Ancel fire dances close to him, although it reawaken his trauma due to the branding. This horrifies Torveld, who is then convinced by Laurent to ask the Regent if he can take the slaves away with him as a gift. Grateful, Erasmus kisses his new master's boot eagerly, in an impressive show of submissiveness which both Damen and Torveld admire, the latter becoming smitten with him instead of Laurent, who is too cold for him.
Erasmus thanks Damen later, telling him he knows he was the one to ask Laurent for help. To Damen's dismay, he says this proves Laurent is kind at heart.