El Dragón despises the very sight of ISIC, as ISIC not only stripped him of his title belt, and ended his winning streak, he violently tore off both of El’s arms in front of a live crowd and completely humiliated him.
Also the assumedly life saving surgery left El in quite a bit of debt, completely bankrupting him.
El also isn’t the biggest fan of his robot arms as he is often criticising their performance, implying that they’re to blame for his failures; “DAMNIT ROBOT ARMS, FIGHT HARDER!!”
So yeah, Dragón and ISIC are a fierce rivalry.
In PVP if Dragón spots ISIC he warns his team mates to ‘watch their arms’, and upon killing ISIC El will loudly shout “JUSTICE FOR MY ARMS!!”