The Wormhole wrote:
Was that line actually written or did Eccleston just ad-lib it on set? I agree that if RTD meant what he said that it was the Ninth Doctor that fought the Time War wouldn't make sense if he wrote that line. But it's possible Eccleston thought it up on the spot and it was kept in because everyone else liked it.
Even if RTD did intend that the Ninth Doctor had fought the time war initially, it seems that by "Journey's End" he had changed his mind, given the talk about how the Ninth Doctor had been "born in battle, full of blood and anger and revenge" like 10.5.
True, not to mention BBC tie-in material does suggest the Eighth Doctor was the one that fought the Time War.
Still, the question of whether the line implying a recent regeneration in Rose was actually written by RTD or ad-libbed by Eccleston is a legitimate one all the same. If for no other reason than simple curiosity.