Azala is the leader of the Reptites. He believes the "apes" to be the inferior race and should either submit to Reptite rule or be destroyed.
Most of the humans went into hiding to avoid getting killed; however, Ayla and the other members of Ioka Villiage stood up to Azala and fought for their lives. And with the help of Crono and his friends destroyed Azala.
The little we do know about him is this - he was originally from 12,000BC. When Lavos appeared in that time, a time portal (gate) opened up and sucked him into it. Belthasar then ended up in the future in the year 2300AD. It is there where he continued his work on what is then known as "the wins of time" (later re-named "EPOCH"). After receiving EPOCH, you will be glad Belthasar finished it as it becomes a very useful item/tool as the game progresses.
What we do know about Gasper is that he was originally from 12,000BC and , like the other Guru's, was an advisor to Queen Zeal. When Lavos appeared in that time, the portal that sucked him in sent him to "The End Of Time". It was here that Crono and his friends meet Gasper. Though it would be a while before we find out his true identity.
Oddly enough, Melchior is seen in both 12,000BC and 1000AD. This is possible because when your party meets him in the Dark Ages, it is before he is sucked into the gate and sent to the future.
It is Melchior who forged the masamune sword, in the year 1000AD he still deals with weapons. It appears that he is the only human living in the town of Medina, the other residents are Mystics. It is here where Crono and his friends meet Melchior.
It is because of this fact that Dalton is jealous of the Prophet (Magus). When the Prophet arrives, Queen Zeal begins to turn to him for advice instead of Dalton.
After Crono's death and the fall of the Kingdom of Zeal, Dalton declares himself to be the new King of Zeal. He steal EPOCH and builds it wings. He also kidnaps the 3 people who are in your party at the time.
Dalton's fate is unknown, the reason for that is while he was battling with those in your party, he gets sucked in to a Golem (a monster of his creation) portal and is never heard from again.
She believed that Lavos was the key to immortality. It is for this reason she has the Guru's build the Mammon Machine. She uses that, along with Schala's pendant to tap into the power Lavos possesses.
She has the Mammon Machine placed with in the Ocean Palace. And for a while it seems as if she will succeed in what she believed to be obtaining immortality, but what in reality was destruction. However, Crono and two others appear to thwart her attempt. But sadly, in an act of bravery to save the others, Crono sacrifices his life. Afterwards, Lavos buries himself back beneath the earth.
What happened to Zeal after this is a mystery. But it appears that she survived the destruction of Ocean Palace and found her way to the Black Omen, that is until Crono and his friends brought about her downfall.