2. The Sontarans
The Sontarans have been an antagonist of the Doctor since his fourth incarnation. This race of cloned warriors are known as some of the most fierce fighters in the galaxy. Aside from Strax, there hasn't been much of a Sontaran presence in the series as of late. With that said, how would the other Sontarans react if they encountered Strax paired up with Lady Vastra and Jenny? Would they be angered that one of their clones has broken their programming and gone rogue?