I got thinking of these two as aspirants again so some lore on that:
After Chyrus completed his first Temple being the Rite of Purity, when given the anima that came with the rite he gained some ascended features. That being his ears.
Throughout his aspirant-hood Chyrus was known for having probably the biggest ears in Bastion. He was less known by his name and more known as the 'big-eared aspirant'. Mercia remembered him because of his big ears which she found adorable. And Adrestes was constantly being asked 'oh where's that big-eared aspirant you're usually with.'
This actually grated on Adrestes more than it did Chyrus. He was almost embarrassed by Chyrus. Ever since he'd been accepted as a Trainee Sentinel and Acolyte of Loyalty, he'd been under a lot more pressure, and it had made Adrestes rather frayed.
He did like Chyrus, but with helping him with his reading (due to his dyslexia) and the constant of being around each other. Adrestes was actually, kind of sick of him.
So Adrestes chose one of his fellow Trainees as a soulbind. Which surprised everyone because like, it was well known Chyrus was his best friend. Chyrus was a little hurt as he could guess something was up, but Adrestes told him he just wanted to focus on Loyalty. Besides, Chyrus didn't even have a Temple at this point, so what did he know?
Thankfully Chryus didn't get Adrestes' hint. And kept asking him to hang out and such. Adrestes' own mentor sort of pulled him aside to tell him, he might want to consider Humility as his next rite. Mercia's good at this kind of conflict.
Adrestes did feel eternally guilty that he nearly completely threw away his and Chyrus' friendship over his own stresses. Ironically it was him who asked to Soulbind with Chyrus when they were both Paragons.