Charybdis was a name that sent fear throughout the old residents of ancient Atlantis.
A being whose very movements created tremors. His breath could wipe out armies and his anger could level all three kingdoms with ease. A beast so fearsome, the three original mermen were forced to antagonise. Through their efforts, they managed to kill the beast and spread peace amongst their people. At least, they thought they killed it.
Unfortunately, at the time, a certain devil saw this as an opportunity to acquire immense power. This devil made a deal with Charybdis with the promise of reviving the sea dragon to full power. All it needed to do was be consumed by the devil. Naturally, one would be sceptical of such a deal, but devils were strictly bound by their words when making a contract. It agreed and was swallowed by the devil, slowly regaining its former strength. While it did this, the devil was also acquiring some of its power.