In Purgatorys Shadow / By Infernos Light from mid Deep Space Nine season 5 is the culmination of the Dominion cold war arc started at the end of Season 2 and the start of the countdown towards all out galactic conflict that dominated the final two seasons. And it is a two-parter that pays off with a multitude of WTF moments. Hundreds of JemHadar warship pouring through the wormhole. Dukat turning traitor to forge an alliance between the Cardassians and the Dominion. The return of the real Martok and Enabran Tain. The obliteration of the Maquis. Nothing for me beat the revelation that the Dr Bashir weve been watching for at least 5 episodes is really a changeling. And its very cleverly done. The dazed real Bashir appears in the Dominion prison that Worf and Garak have been taken to, wearing the old Starfleet Uniform. A uniform that was replaced with the grey First Contact uniform earlier that season. This meant he had been a prisoner for a couple of months, maybe more. By this point I had really warmed to Bashir and to realise that he gone through this ordeal was dramatic moment for his character and the audience. And the changeling Bashir? Its interesting to note that even the writers seemed to have failed to realise Bashir was a changeling. They had him perform brain surgery on Sisko a few episodes earlier, which comes across as rather an odd thing for his enemy to do. That being said, we were rewarded with a thrilling sequence where changeling-Bashir sets out to destroy Bajors sun and wipe out Deep Space Nine in the process. I think that makes him a worthy villain.