A little ben 10 universe lore.
Ive always imagined gwen and kevin to be same sides of the same coin.
Like kevin absorbs energy whereas gwen radiates it. And tracing back their ancestory , their home planets actually exist together, in a sort of magnetic sense where one really cant live without the other.
Okay so long ago, the celestaspiens had 2 twin girls, and they both inherited a power each. One got osomosian powers and one anodite.
During their birth, other beings kind in their vicinity got their left over powers , giving rise to the osmosian and anodite race.
They were good species, got along with other aliens as well till some decided to take advantage.
Some osmosians were trapped and used like how kevin was in AF for taydenite , anodites were kidnapped for power source, and very few from both planets went rogue and murdered people.
So the sisters decided it was better to cut themsleves off from other specoes, only interacting if actually needed.
Which is why you dont see a lot of osmosians and anodites around casually, but you see other aliens.
I also have a headcanon that when devin left to join the plumbers , the osmosian queen had strictly instructed him to send over any child he has because she was worried any osmosian child outside her protection would be harmed.
Devin died before he could send kevin over, otherwise kevin was supposed to grow and learn power control on osmos and only then would he have been allowed to leave the planet to do whatever he wanted.
Verdona was also supposed to do something similar, which is why she came back to check if anyone had inherited powers and did really try to bring gwen to anodyne because the anodyne queen had similar rules.
A lot of alien species view osmosians and anodites as snobby monsters because the two races are far too powerful and the few who went rogue really did a number on the lower race aliens.
Which is why Max did not care for kevin being a child when he threw him into the nullvoid, and also why he favours ben over gwen.
There this inbuilt level of raceism( aliensim?) Within Max and quite a few plumbers.
They tolerate kevin and gwen but will not hesitate to take them out the second they slip up.
I do headcanon kevin at some point does go to osmos and gwen to anodyne, not to live forever but to see wherw they come from.
Kevins surprised to see the osmosians are actually nerdy and uptight, and the gwen to see the anodites are waay to free and careless.
The sister queens are the most powerful amongst the races ( duh lol) and have been around forever.
Theyre also pretty chill with each other, constantly teasing and playing pranks.