IRONBOUND

The story follows our Solin, who is a hero for the mecha people. In this society, everyone has characteristics of a specific species and a secondary form of that species (like how werewolves can be in a human form and a wolf form). The mecha people are part machine and are the only species that have physical characteristics of their species without a secondary form. This hero is the only one who can. In this society, they use portals for fast access, and there is a rule that after 10 years of the portal opening, whoever has control of that area is given full control of this portal. A new portal opens close to the dragon race and the mecha people. At the time of the portal opening, the mecha people were considered the lowest class. Our main character had lost his parents at 11 and was captured by his own people and forced into experiments to force a secondary transformation. He was the most successful story and was forced into a position of fighting the other species almost daily. He killed thousands of the dragon race, and every kill pained him. When the fighting finally stopped at the end of the day, he would hold funerals for the dead as a form of respect. Several years into his fighting, a very might dragon arrived.
Ironbound is powerful, emotional, and totally captures the heart of your story - a warrior bound by metal, by duty, by grief... and eventually, by love.