Tell me!

Ren had lost consciousness for a second but within that second Edge Regius took over his body. This forced Ren to once again enter the realm inside his soul which was inhabited by his past incarnations.

When Ren saw this he was immediately furious. This was the second time he was denied the end of a fight. He would have rather died in battle than being denied to fight until the end. He could understand the first time since that was beyond his control. But this time he was possessed without his permission again and in the middle of a fight no less. This left Ren fuming with rage. 

"WHY THE HELL DID YOU DO THAT!" No longer able to control his rage because of all the accumulating stress he had received. From the time Nezzard fled with his Spirit Rulers after getting him excited, to the time he was denied the ending of his battle with Lance, and now this.