I'm approaching this as a
totally hypothetical situation, one which I.M.H.O. could
never have happened because of the purity of Ramza's heart. He's just too good of a man to ever turn a blind eye to the injustice that was so rampant in Ivalice.
If hypothetically he
had sided with Dycedarg, call it family loyalty taking absolute priority over his own personal morals, whatever, he would have continued to aid Dycedarg until one particular event would have swung him drastically back to the other side. And I'll elaborate more on that thought later.
When he was allied with Dycedarg he would have agreed with Algus, that his responsibility to his noble family took priority over his friendship to Delita even as Delita's
(SPOILER) rage over his sister's kidnapping led him to fight and kill Algus. Ramza would have done his best to save Algus, possibly at the cost of his or Delita's life. This is a crucial turning point in the story which would have been different if Ramza's loyalties had laid with his brother.
From this point on there may have been no
(SPOILER)kidnapping of Ovelia from Igros Castle, at least not by Delita. And Ramza would have continued to aid his family in "protecting" the Princess until his brother probably would explain how it would be "better for the Beoulve family" if they
(SPOILER)were to stage a ruse, a fake kidnapping where Goltana sent somebody to take her. Thus making Goltana and the Nanten criminals. If the princess were to be "killed by the Nanten", even better for the Beoulves. I imagine Dycedarg would probably trick Gaffgarion into
(SPOILER)being the martyred patsy for this plot, since Gaff could play a rather convincing T.G. Cid, only to have Ramza, and maybe Algus, betray Gaffgarion at some point to keep everything a secret.
(SPOILER)The Church's plot, and Vormav's hidden agenda would also come into play. As Rofel visited Dycedarg
(SPOILER)to confront him about the assassination of Balbanes some time ago, and blackmail him into aiding the Lucavi in some way. Here is where Ramza's loyalties probably would have switched back to the way they were in the game.
(SPOILER)IF Zalbag had still overheard the conversation between Rofel and Dycedarg, and had been able to convince Ramza by taking him to the grave to see the evidence of mosfungus poison. Ramza would have reacted in the same way as Zalbag did in reality.
(SPOILER)A son's loyalty to his father would have taken priority over loyalty to a traitorous brother. Thus, together Ramza and Zalbag would have
(SPOILER)confronted their brother, who by this time would probably have been possessed by the Lucavi Adramelk. And the outcome of that battle would have been pretty much the same as we know it.
At this point Ramza is back on the "right" side, now whether or not they
(SPOILER)still have time to stop the other Lucavi and the plan to resurrect Ajora by using Alma, is another topic for debate that we could cover in a different thread. I'd love that!