Sunspot absorbs ambient energy through biological processes, turns it into raw energy which he can use in three main ways. Sunspot can channel this raw energy to increase his natural strength up to about 50 tons. However, there is no increase in bodily endurance. He can also channel this energy as blasts of concussive force, ranging from a large radius blast to a precision laser type blast. By projecting this energy downwards, he can fly in a manner similar to Cannonball, a.k.a. Sam Guthrie. Sunspot's greatest effects are achieved when he's in direct sunlight, as he must absorb it before unleashing it.

He can store a great deal of sunlight in his body, and continually absorbs solar energy at all times. As an aftereffect of his mutant power and the encounter with the malevolent psionic entity Reignfire, black crackling energies cross his body at all times.

Robert DaCosta is the son of Emmanuel DaCosta, a rich Brazilian Industrialist, who later became a member of the Inner Circle of the Hellfire Club, and Nina DaCosta, an archaeologist. He is one of the original New Mutants, though it was not marked by happiness (his girlfriend was killed by Hellfire Club agents). Later, one of the New Mutant training sessions, he injured Sam Guthrie when he lost his temper. He left the team, wondering if he could really be hero material, followed by the New Mutant Warlock. He joined the Fallen Angels for a short period of time before returning to the New Mutants.

Roberto stayed with the New Mutants until his father was killed by Gideon (an External), though it was blamed on Cable, who was currently leading the New Mutants at the time. Roberto went back home to manage his family's business under the tutelage of Gideon. After a while he began to question what Gideon was teaching him and in response Gideon captured him and took him to a secret research facility. X-Force came to rescue him, but not before the experiments developed new aspects of his power, flight and solar blasts.

Roberto stayed with X-Force, eventually finding out the truth of his father's death. Staying with the X-Force, he was eventually lost in a battle with the MLF when his powers interacted strangely with the powers of an MLF'er, Locus, a teleporter. The two disappeared in the interaction of energies. He wasn't seen until sometime later when X-Force made a coordinated search for him. In a surprising turn of events, it was revealed that Roberto was actually Reignfire, the current leader of the MLF, teleported back and forth in time by Locus. He was psionically possessed by this being and his whole mentality was restructured. In a psionic duel, Cable forced Reignfire out of Roberto's mindbut his powers became increased so that his body possessed solar energy at all times (resulting in him always being covered by the crackling energy field).

Roberto has stayed with X-Force, trying to put Reignfire behind him. His power levels have also unexpectedly increased, as well as the fact that Cable's psionic tampering has imprinted Cable's Askani teachings.