OK so I'm new to the series and watched it pretty much out of order. I'm catching up on the episodes i never saw but cant help myself when i see it on tv. So i wound up watching the season four finale, both parts, and i was wondering how that ending could possibly make sense.
If Donna had to be wiped of her memories because a time lord human biological meta crisis was not suppose to exist and would kill her, then how would the now part human Doctor, who stood at bad wolf bay with Rose, be any different? Maybe he was just talking to fast and using to many big words for me to understand but if the time lord human biological meta crisis worked both ways and the second Doctor became human but was still a time lord then how come he wouldnt face the same fate as Donna? Why would the real Doctor leave him with Rose under the impression that they could spend their life together?