Steve, A.K.A. Experiment 436, is an illegal genetic experiment created by Jumba Jookiba. He is designed to generate excessive and unstable energy.
Experiment 436 was the 436th genetic experiment created by Jumba with Hämsterviel's funding. He was designed to generate excessive and unstable energy (does so by containing the destructive power of a supernova inside his body).
436 and the other first 624 experiments were deactivated and smuggled to Earth by Jumba during his mission to capture Experiment 626.
All of the experiment pods were released and scattered across the island of Kauai.
At the unknown point, he was activated, captured, tamed and named Steve.
After experiment 436 is activated the power in his body steadily increases until it reaches a critical level.
The only way to neutralize experiment 436 is to syphon off the power that he generates.