Okay here is something I wondered upon discovery the fact that Hiro had other plans for the Tower of Heaven arc, and Trinity Raven were never suppose to exist, could be why we have seen them again.
Hiro original plan was for Erza's old friends Simon, Wally, Shu, and Milliana to fight the battles that Trinity Raven fought.
My question is what if Hiro went with this original plan of having Erza's friends fight the battles with our heroes that Trinity Raven ended up fighting?
Who would have fought who, who's role would they end up playing. At first glance, people would assume Milliana would take Ikaruga role because they are both female, I disagree. I think it would have been Simon. I think he still would have been an double agent and die protecting Erza from Jellal at the climax of the arc. But he would have fought Erza, either because Jellal's watching so he has maintain that illusion on being on his side or he doesn't think Erza is strong enough to fight Jellal and wants to protect her from herself. I think Erza would defeat him and than he would reveal his true intention, and they go together to confront Jellal. Hiro probably wasn't thinking that far ahead, but that is also good set up for Erza vs Kagura down the line.
I think Shu would have fought Gray and played Fukuro's role. Shu did have the stubbernish that he is on right side, so he would have Fukuro fight for justice.
That leave Millianna and Wally to fight Lucy and Juvia in Vidaldus Taka's place. I think all along Hiro wanted Lucy and Juvia to team up, to put the whole Lucy's kidnapping behind them, and let us know the despite the love rival joke, Juvia doesn't hate Lucy. Vidaldus Taka was the only one to get a two on one fight, while the others got one on one fights. Granted I don't know how Millianna and Wally could do something to equal Vidaldus powers of turning Juvia evil.
Another theory, Jellal's assistant that turned out to be Vidaldus, was that originally suppose to be Ultear?, I mean Jellal was able to be in two places at once with the Serigan's alto ego, surely Ultear could have done the same. And we know she can shape shift into a guy.