There may be multiple versions of Cassie 12,000...But one thing is for sure.She has a upgraded blue and white version of the Omnidewtrix in Omniverse style.
Cassie 12,000 has been predicted to live like any ordinary person without revealing her fame or people knowing she can go Ocean Alien unlike Ben 10,000 who has unlocked 2,000 less than her Aliens. But it's known most definetly in Cassie 12,000 She'll keep the watch on and get together with Gastro. Sooner or later, she will have a daughter named Lassie.
It's also been hinted Harvey from My gigantic camping trip may be the Uncle of Lassie if Stallion passed away in the future.
In Cassie 12,000, Cassie used the watch to do violent things searching for OSG which has not been menioned or told yet,But what OSG told Younger Cassie totally freaked her out. Nearly a good portion of her life was aimed on catching the mutant villian.
It's unknown if OSG was killed or sent to the null void at the end.
In the supposedly season two and three of C12; ver the first two seasons of Cassie 12: Original Series, Cassie has evolved into a easily tipped off girl who will get anyything done in her way and will help her friends if they need help from her. It's also been hinted she has grown feelings for Gastroaftera year of villianless.
Still some things make her pause and think, so Cassie's not even surprised to see what the Villains have in store for her return...these days.
In the last episodes of season 3, Cassie is shown to be devious and somewhat grown to the aspect of wielding a Watch. Her friendship with Anna leads her into understanding what her friend has to cry or be mad about from learning the truth. She's more like your average teen with a Omnitrix than a adventureous girl from a year ago.
At the end of season 3 of Cassie 12, it's revealed these events never happened and Cassie has removed her Omnidewtrix at the end of the summer. It's implied she used all twelve Aliens throughoyt the summer vacation.