I am quite curious on what the relationship between Jellal and Erza would be if Erza stayed trapped in the Tower of Heaven by Jellal instead of thrown out.

This is just me going off on one so you can just ignore the post.

But what if Erza stayed by Jellal's side instead of being pushed away? What if she was manipulated and had her mind broken by the maniputive torture that Jellal put her through?

Like Erza won't be the woman we all know her to be, she would be a trapper, mentally broken woman, who only knows how to follow the orders of her master.

Considering she never met Fairy Tail, thus never met Natsu or any one from the guild (aside from Grandpa Rob), no one would have been able to defeat Jellal and "kill" him (in other words), so Erza is forever trapped to be by Jellal's side.

I would also believe that the plan (I cannot remember what it's called) would have been a success. The magic council would be too late to realise that Earthland would be destroyed and all.

Erza would remain by Jellal's side until her last breath. Like a Puppet to a puppeteer.