Nexus is a virus created by Miles Dread sixteen years prior to the series' events.
Nexus was created by Dread before Makino's invasion. The virus would instantly corrupt Makino's systems and ultimately would fatally harm him. However, it turns out that Makino could simply absorb the virus and become even stronger, as Jim stated before Dread actually created it. After all, however, this didn't stopped Miles from creating the virus.
Sixteen years later, after Ferrus discovers about Dread's betrayal, he asks to Berto create a robotic body that would contain the virus and prevent him from spreading and infecting electronic devices around the world. The virus was kept under a base with heavy weaponry disguised by a grave.
All of sudden, the robotic body started to move and showed to be alive. He wanted to absorb electric energy and encrusted his arm into a panel in his front, thus getting information of that base and realizing that he was being watched. He sess a camera and destroys it, but before he does so, he says "Smile for the picture!" and later on running away, maniacally laughing. He was wandering the base and wanted to consume electric energy.
After realizing that Nexus was activated, Ferrus sent Max and Team Turbo to contain him before he destroys the base and eventually escapes, thus causing a catastrophe of great proportions.
He is stronger, more durable and faster than an average individual. He is capable of consuming the energy of electronic devices and can infect machines (like C.Y.T.R.O., for instance) with his virus. He can also easily hack technology and if he is destroyed, he can transform himself into a red liquid capable of turning a person, or a machine, into his new host.
Nexus' appearance may vary according to the host that he linked with. A remarkable chararacteristic on every host that he had possessed was the large smile and red eyes.