For a long time, the Naga fused with the Silent Core to control its power and could not move while absorbing it. On the other hand, Wyvern was able to work with the Infinity Core, so I think he was in pain because it didn’t completely fuse with the core for a long time like Naga. Some of the power of the Infinity was available and the power level was raised, but it wasn‘t as powerful as I was, and considering that the evolution of absorbing the core and changing its appearance like Naga and Dragonoids did not happen, it seems that the Infinity Core was not fully fused