My Wild Mass Guess of Sigma and Lumine in Megaman X8
Megaman X8 features a more or less complicated game plot with Sigma's rule and the last minute turn of Lumine being the final antagonist. Lumine starts off being portrayed as a person kidnapped by Vile, to which was ordered by Sigma. But surprise, surprise when we finally beat Sigma in normal or hard mode...
After defeating Sigma, Lumine reveals that Sigma helped his plan which either he was the real mastermind or this was a backfired scheme. Apparently, Sigma may have cooperated with Lumine behind the scenes to make the new generation reploids. Sigma's DNA is almost everywhere in this "evolution project" which in turn, Lumine may also have had Sigma's DNA. Again Sigma could return one day.
My only speculation is this- Sigma intends to betray Lumine and vice-versa. However Lumine knowing of Sigma's lunacy had increased, he takes advantage of it. Only after Sigma fell did he reveal his true purpose- that Sigma was merely a "tool". So either way, Lumine double-crossed Sigma, a fitting fate for the main villain. Which again, betrayal because Sigma had already double-crossed several people throughout the series and Lumine was the acting karma.