After the reopening of the Scholomance at the end of the Dark War, Milo was one of the Shadowhunters who attended the school and became a Centurion. At some point, he was recruited by his friend and fellow Centurion Zara into the Cohort, a group led by Zara’s father, Horace Dearborn.
In 2012, he was among the group of members of the Cohort that upon finding Kieran, a faerie prince, hiding in Diego Rosales's room in the Scholomance, tortured him and dragged him to the Hollow Place, with the intention of throwing Kieran into the enchanted pool, possibly killing him.
Shortly after, Milo, among the group led by Manuel Villalobos, went to the campsite set up in Brocelind Forest by some members of Livia's Watch to kill Jace Herondale and Clary Fairchild. They were ambushed and caught by the Shadowhunters and Downworlders waiting in the camp and taken to the Imperishable Fields.
There he participated in the battle that unfolded during the Cohort's parley and fought alongside the Cohort and the Unseelie faeries against Downworlders and his fellow Shadowhunters. The Cohort lost the battle and Milo, along with all the members who took part in the fight, was taken prisoner to the Gard where he was tested by the Mortal Sword and confessed his crimes.
During the meeting that followed in the Council Hall for the Cohort's trial, he was entitled the right to vote for the Clave’s new Consul, but when Alec Lightwood was elected, he and his comrades refused to accept his authority and threatened to commit suicide if the non-supporters of the Cohort didn’t leave Idris permanently. They watched as Amelia stabbed herself in the stomach to prove to them how serious they were and when Alec chose to submit to their terms, he stayed with the others in Alicante.
Milo has a muscular build.
- Queen of Air and Darkness (first appearance)