What was Riddick injecting himself with?
Could you please elaborate on the context of the question "What was Riddick injecting himself with?"? Is this from a specific movie, book, or other media? Without that information, it's difficult to give a precise answer. However, in general, if Riddick is a character who is seen injecting himself with something, it could be a variety of substances, such as a performance-enhancing drug, a medication for a medical condition, or even a recreational drug. It all depends on the context and motivations of the character and the story being told. Without more information, it's difficult to speculate further.