[quote=@Stern Algorithm][@Dead Cruiser], as for a 'digivolving Kamen Rider', I think the power is totally fine.  The main limitation with aliens is a political one.  The Jarav have to let the Preceptors on Earth because of the treaty, but for any other alien species, the Jarav will filter.  Aliens are not allowed to give information or share technology, they have to let humans learn and grow naturally.  The alien is allowed entry if they are 'here to help', which usually just means that they're allowed to be superheroes.  So the Jarav won't let aliens who have no business being on Earth on Earth.  So your character's alien parent is either a superhero (or was a superhero), or someone who doesn't care about the Jarav blockade and is living (or has lived) on Earth illegally.  Also, most aliens don't care about Earth and the preceptors are incapable of mating.  So explain your alien parent to me and we'll see.
[/quote]

My idea is for something like a less malevolent version of the C'Tan from Warhammer. Imagine a race of energy beings that live inside of and feed on stars. Perhaps due to their parasitic nature, they stay under the radar in regards to the Canon, and as such are unknown to the Jarav.

From here on my ideas are a little hazy, and I could use some help ironing them out. Perhaps with the arrival of the Jarav, the Star Vampire saw its secrecy within Sol as jeopardized, and fled to hide within a human form. Potentially, it has been literally inside of humans for generations, resulting in a long line of metahumans with its power within them. Thoughts, or better ideas?