Emery had experienced and seen first-hand how much humans hated the Fey. His family estate was completely burned to the ground and his father mercilessly killed, all because of loving a Fey, his mother.
Even so, he was reminded of a certain princess who, despite also harboring deep hatred toward the Fey, still accepted, lived with them, and in times brought peace between humans and the fey.
Although it couldn't be compared with what was happening in the Ouroboros, Emery still wanted to believe. He needed to believe a peaceful coexistence between the half-blood and humans was possible in the future.
During the hours he contemplated his decision, Emery kept coming back to put his home, Earth, above anything else. No matter how much he tried to look at it from another perspective, the support, the opportunity, he just could not shake the feeling that joining the Ouroboros would endanger his home, his friends, and his responsibility to them.