Lettie the Pusher (Superhero Black Hole, part 97)

"How is she making more time-travellers," I asked him.

"After the reactor exploded, the fallout area contained extraordinarily high levels of radiation - the same radiation that rippled throughout Time and created time-travellers in various points of the Past. Letrodacta was already long affected by this radiation, so was essentially immune to it when she ventured into Ground Zero and collected a massive amount of the radioactive waste to store in one of her military research facilities. "She then distilled the radioactive waste into a purely chemical compound. And once she had perfected this process, she started aquiring random members of the public with which to inject this compound, and thus create new time-travellers. "Unfortunately, these subjects of hers are far too clumsy with their powers. They jump backwards in time, re-write history, alter too many things, and wind up getting killed."

"And this is what she wants to happen?," I said.

"It's the only reason she ever had for doing any of this."