When Armando Munoz was four his father left his family. Armando's mother told him it was because there was something wrong with him. He grew up in the face of rejection. Even his own mother despised him, but he didn't hate her for that. He did everything he could to make her love him. A day came when he was asked to take an IQ test. Unknown to anyone at the time, Armando's desire to impress his mother subconsciously activated his mutant power and allowed him to test off the charts. He was quickly enrolled in a renowned boarding school, the Biltmore Academy, but he was sent away mostly because his mother hated him. He had trouble making friends, and was often picked on. Some bullies tried to stick his head in the toilet one afternoon and Armando realized he could breathe underwater. When his head came out of the toilet he punched the bullies but his hands were made of stone. He still did not understand what had happened or that he was a mutant. A year later Armando was visiting home, and his mother attempted to burn down their house with both of them inside. Armando woke up to his mother lying in the flames, and without thinking he scooped her up and ran through the fire to safety. Firefighters were shocked to find his skin wet and smooth instead of severely burned. After that day, scientists at Biltmore started doing tests on him to find out the extent of his powers. Armando's eyes would see in darkness and his lungs would close up in a room full of poisonous gas. The scientists named him, Darwin the evolving boy. That was when Armando first understood he was a mutant, but this was also why his mother disowned him. After having an argument with his mom, he attempted to commit suicide by jumping of the roof of the school, but he nearly bounced when he hit the ground. Days later a man came to recruit Darwin for Moira MacTaggert and her school.

Little is known about the time that Darwin spent on Muir Island, but it is known that he was one of the the four students that Charles Xavier recruited to rescue the X-Men from Krakoa. He seemingly died during this encounter, but was later revealed to have survived by merging with his teammate, Vulcan, who also survived.

Darwin absorbed the remains of the two girls and then converted himself into energy to fuse together with Vulcan. This gave Vulcan the powers of Darwin, Petra and Sway. Marvel Girl (Rachel Summers) managed to expel Darwin's presence from Vulcan, who then took off for space. While dealing with the shocking revelations of the truth about Krakoa and Vulcan, Beast found out that Darwin was still in fact alive. He was brought back to the Institute, where Beast determined Darwin is now a being of pure energy. While not conscious, he was shown to still have brain activity and was still alive, located at the X-Mansion.

When the X-Men team including Warpath, Havok, Polaris, Marvel Girl, Nightcrawler, and Professor Xavier left to go hunt down Vulcan and stop him from destroying the Shi'ar, it was revealed that the Professor brought Darwin with them with hope that his friendship with Vulcan would help control his rage. When Shi'ar agents abducted Professor X, Darwin followed, and secretly jumped onto their spacecraft as it fled.