The new Killer Instinct title that released alongside the Xbox One chose to take an interesting approach with a free-to-play model. For free, you can play as one free character, which rotates over time. At launch, Jago was the playable character, but now that character has been changed to Sabrewulf for the near future.
As part of a new patch for the game, you can only play as Sabrewulf as part of the free version. You can still of course choose to buy either of the available paid version to gain access to the six currently playable characters. You do also have the option to buy characters individually, so if you don’t want to spend the full amount but want to have Jago back, you can purchase him for $5.
To see the changes made in the patch besides changing the free character, you can check out the forums post on the Double Helix website here.