As is usually the case with most Wardens, the gem found her after she was humbled. A former BMX racer, a number of circumstances spawning from her own mistakes left her homeless. After finding shelter with an old friend, the gem arrived and she used it as a chance to jumpstart her turned-around life. However, she skipped the nomenclature trend of light-based hero names and simply settles for Impact.
It's worth noting that despite being a white Star Warden (the ones in "harmony") ... it doesn't necessarily mean they're peaceful. It really just means they have enough intellect and scope to consider all the options. She's more than willing to shut down badguys with her fists. So much so that her original crystal/gem actually broke during combat. She's since turned the shards into knuckles.
Also ... she's a half-orc. In happenstance, this is a misnomer, but one that's persisted. Orcs actually lack traditional reproductive capabilities (they're largely constructs made from spawn pits, spores, or other means) ... this means there can't literally be half-orc-anything. Half-orcs, as they're called, share several similar qualities to traditional orcs ... but have full reproductive cycles and age normally. Due to brain chemicals, they tend to be a bit more short tempered and loyal than other species. Naturally (similar to orcs) there's a bit of range in skin tone, anatomy, etc. Half orcs are also a bit more human in appearance. Impact here, for example, doesn't have protruding tusks, though when she smiles she clearly has extended teeth that fit within her mouth.
** it's worth noting that their origin as a general species is unknown to scientists.