Tiva Stormbringer is a celestial storm spirit. During the Qularr invasion, Livewire said a prayer that she be guided by "whatever power is up there" and Tiva was randomly selected to answer that prayer. Due to the ambiguous and noncommittal nature of the prayer, there was no way to complete it nor was there an escape clause and Tiva was stuck on Earth until Livewire no longer needed guidance. Her guidance started out being more hands-on, but has moved to that of a personal advisor that's rarely seen.
Tiva may be older than your ancestors, or your country for that matter, but she is still a teenager in the eyes of her godlike celestial peers, and she still has normal adolescent interests, like watching boys, shoe shopping, squealing over finding the perfect scrunchie that she will never actually wear, listening to brain-rotting heavy music (her favorite bands are Arch Enemy and Kittie), and throwing tantrums when nothing lives up to her impossibly high expectations.
Motivated solely by the desire to do the right thing, and not really caring about the people she's helping, Tiva has become a minor heroic figure, and is a member of UNITY in good standing. It is fair to note that she is extremely dangerous with a volatile personality, though she should not be approached with caution, but instead with confidence and respect, as cowardice and creepiness are the two things most likely to anger her.
Tiva's relationship with Livewire is that of a live-in personal confidant and life coach. Tiva lives in Livewire's penthouse suite in Millenium City when she's not out roaming the world, and helps to keep the reformed villain on the "path of awesome" which is an ambiguous mixture of altruistic and apathetic: they help people not because they care, but because it's the right thing to do. Tiva urges Livewire, and anyone else she meets, to "grow some conviction" and "pick a side and stay there". Tiva also helps to clear up Livewire's personal drama by giving her the confidence to rise above it and point out that whatever it is actually doesn't matter.
Tiva met Barry Winters (aka Crusher Blue) shortly after the Qularr invasion. He was a fledgling hero trying to make a name for himself in the wake of that disaster during the cleanup. The two formed a healer/tank team that couldn't be beat, and Westside will forever be in their debt for their contributions to putting down gang violence. The two were romantically involved, and Tiva even moved in with him for a while. However, it was not meant to be: Crusher Blue found VIPER's recruitment offer a tough deal to beat. He tried to enlist Tiva and Livewire as well, but he found their combined resistance to the idea ... shocking. Since then, he's become her nemesis, allying with everybody from Shadow Destroyer to Cyberlord to try to get back at his one-time lover. He remains a retainer in VIPER's mercenary forces, though, and commands a small force of mercs to help him.
Tiva has, on at least one occasion, put on one of Livewire's costumes and shown up to put down a villian. It's obvious from a moderate distance that this slender girl doesn't fill out the costume properly, and her hair isn't right, though from a distance, the signature costume and the bright orange lightning arcs make the two hard to tell apart. Pursuing the possibility of a super-heroic identity of her own, she occasionally wears some gaudy tights and calls herself Shock (named in honor of a Fear Factory song), changing her power aura to a light blue and playing down her healing abilities.
Most of the time, though, Tiva is comfortable just being herself without the showy theatrics of earthly heroic types.