Mega Man 8: Part 6: Mid Stage (Encountering Duo!)
3After beating the first 4 Robot Masters, Mega Man returns to Dr. Light's lab with some dark energy resources that he picked up along the way. They are literally out of this world, and there are still more to find before Dr. Wily does. So they left to see if they can find another energy emission to track him with.
Beforehand, Dr. Light was fixing up the big robot that Mega Man found in the islands. He suddenly wakes up and destroys the dark energy resources, remembering the enemy he faced in space. He then escapes to hunt down more of those resources at a fortress, forcing Mega Man come back and chase after him.
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The following stage is pretty short, but there are still bolts you can find here for Roll.
The big robot that escaped is called Duo, when Mega Man finds him, he attacks, thinking that he is an enemy. His only attacks are to jump on you, punch you into the earth, or "pull a Pulseman" and perform a Voltteccer for a couple of seconds. Just keep dodging, jumping and shooting and Duo will be done.
But he isn't killed, he just stops fighting because he noticed that Mega Man was holding back on him and that he wasn't an enemy. Mega Man, likewise, felt the same way.
Suddenly, Mega Man's older brother, Proto Man, appears to see what happend between Mega Man and Duo's fight. Proto Man knows that up ahead is Wily Tower, where Duo was heading towards, so he leaves it to Mega Man to go after him and see if they can both get Wily.
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Mega Man and Rush do indeed find Wily Tower, deep inside of a volcano. Mega Man dives in towards, but it grabbed by a giant evil robot that Wily send after him. Rush tried to jump in and help, but he only ended up getting punched through a wall with the saddest look on his face, ever.
After complimenting Mega Man for getting this far, Wily then used that big robot to zap Mega Man to death. Mega Man managed to survive this for over 20 SECONDS! Then he was broken free by Duo, who then proceeded to make short work of the robot that almost killed Mega Man. He even managed to get another evil energy resource from it and formally introduce himself. Duo's job is to eliminate it all, because if Wily manages to get his hand on it all, his own evil will multiply and he could possibly become unstoppable for the Earth.
Before anyone of them can get inside Wily Tower, its barrier must be deactivated, first. Duo will hunt for more evil energy, while Mega Man finds the remaining 4 Robot Masters in order to beat them and shut down that tower's barrier!