Previously a believer of the local religion, Ren joined Tyre originally as a religious follower after being introduced to it by Takeo. He was originally sceptical of the theory of the Four Fiends being on Edia, though he respected Tyre still for propheting Lucter's words even in strange lands.
Ren also originally did not join the party's shift to a more military gathering, until a while after he was requested by Takeo specifically to forge weapons for them. He originally just provided these weapons, supporting their view and actions but not actively participating. Ren fully joined the team when they were making preparations to leave, passing his job as a smith on to his son and student Kagari.
Ren had a wife and three children, two who were still very young when their father died. Ren's oldest child Kagari was an adoptive son, who was a far cousin but taken into the family to become a swordsmith and help the family. At that time, Ren had already been married for several years while his wife was unable to give him a son, whereas Kagari was the youngest of six children, five of whom boys.