David Tennant's human-Time Lord hybrid was originally meant to be a proper villain on Doctor Who, says former showrunner Russell T. Davies. Tennant is best known for playing the Tenth Doctor on the long-running hit BBC series. The epic finale of the Tenth Doctor's final season featured the Doctor not only facing Davros, but also another potentially far worse enemy: himself.
It's become somewhat of an unwritten tradition that each incarnation of the Doctor goes out with a bang before he regenerates into the next face. The Tenth Doctor's season four finale was no exception. "Journey's End" featured all of the Tenth Doctor's companions coming together to help the Doctor save the universe. Fans were shocked when it appeared that the Doctor was about to regenerate before the finale's end, but in a shocking twist his regeneration energy ended up creating a human/Time Lord hybrid Doctor clone. The real Doctor ends up leaving the clone Doctor in a parallel universe with Rose Tyler, fearful of the clone Doctor's rage after he gleefully committed genocide against the Daleks.
According to Davies, the clone was originally meant to be even more a villain than in the final cut of the episode. The writer took to Twitter to live-tweet the iconic two-part finale with fans. Davies offered interesting behind-the-scenes insight on the episodes, as well as plot details and character beats he ultimately had to cut due to budget. Check out Davies's description below elaborating on how he originally intended to write the Tenth Doctor's clone.
In a way, the clone Doctor did act somewhat as a villain. The real Doctor himself explains to Rose that his clone was in fact him, and could've still been him if Rose hadn't softened his murderous and dark edge. After all, Rose Tyler met the Doctor in his ninth regeneration, when he was still rather shell-shocked from the great Time War. While Davies's original intentions with the Doctor clone are rather interesting, the final cut of the episode was satisfying because it focused on wrapping things up for all of the Tenth Doctor's companions. There are still fan debates to this day if Rose was given a proper ending what with being stuck in an alternate universe with a clone Doctor. However, one thing that defined the Davies era of Doctor Who wasn't just the fan-favorite Tenth Doctor, but his incredible array of companions. Ultimately, keeping the focus on those characters was the right choice in the end.
Russell T. Davies's tenure on Doctor Who ended with the Tenth Doctor. It's worth noting that Doctor Who may not have had a successful regeneration after being off the air since 1989 if it hadn't been for Davies work as showrunner and writer. He brought us the Ninth and Tenth Doctors, introduced the concept of the Time War, and paved the way for future Doctors and show runners to keep the Time Lord regenerating for hopefully years to come. As the Tenth Doctor always said, allonsy!
Source: Russell T. Davies