Cassie -
Cassie, in Beast Killer, is the Dark Type Gym Leader in Johto, and her Gym is a small town by the sea called Andromeda. It's called such because the town practically runs in the night; When the sun goes down, the town goes from a sleepy place to a fast, wild and battle centered scene. At the Arena, trainers of all kinds come to battle each other, and then battle the victor; Like Johto's League all in the span of a single weekend.
In the Trainer game since her early youth, Cassie pursued the eight gyms in all of Johto, eligible to challenge the Elite Four, but Cassie had another idea in mind, and it lied all the way at the sea.
Cassie battled alongside many trainers in the Arena for years, growing with her team of Dark type Pokemon. When she turned 25, she finally battled her parents, the leaders of the Arena one last time, and triumphed. Retiring, they gave Cassie the ownership of the Arena.
Nowadays, Cassie helps the entirety of Andromeda, overseeing its growth, while challenging trainers and giving the strongest, most captivating trainers a chance to be her Arena trainers. Very few have the honor.
Since Cassie left home to become the very best, she hasn't had very much time to be with her brother, outside of texts and brief phone calls. They finally unite again, on one chilly night, with a beast unlike anything they've ever seen, on their dining room table...
Damien -
Damien, in Beast Killer, is Cassie's only brother, and she's his only sister. Born and raised in a sea-side, forest town in Johto, Damien took up a quieter lifestyle behind the spotlight unlike his twin sister, but that's not to say that Damien isn't active. He spent most of this adult life weaving into the way of Pokemon research, assisting famous professors in Johto and eventually branching off into his own business in Goldenrod, studying Pokemon through bones and fossils, from common types to Legendary Pokemon.
During Winter, Damien takes an end of the year break to come back home to Andromeda, where he'll stay at the old family home far in the forest. Fish are abundant, logs are perfect for nightly fires, and with his old Mightyena, he's quite content with the peaceful life.
One year, however, his work followed him home. Rather, it washed up on the shore of a lake, far from civilization, but right into Damien's hands. A creature, grand and mysterious, almost dead...Damien does something he hasn't done in a long time, and calls his sister one more time. If he's going to unravel a mystery, he can't do it alone anymore.
Echo -
"Hi there! I'm Echo, do you wanna battle?" From a young Echo, to a young air headed Cassie, somewhere on the way to championship. Bold and confident, a grand battle took place in a meadow, and Cassie was blown away - literally! - at her young friend's strength. She said to them,
"Do you wanna come with me? I'm going on an adventure!" and they replied "Always! Friends?"
"Friends."
Years passed, and Echo came to make a temporary home in Andromeda, where the sea always gives them something to do, something to paint, and a sense of freedom. Cassie's trusted friend, when she became the Arena leader, the first thing she did was appoint Echo as the first and highest trainer, unbeatable to this night.
People want to ask questions, get advice, interview them personally, but they can never find Echo once the battle is over. It's almost like they vanish with the tides...
Playful and mischievous, Echo also has a deep spot for Pokemon of all kinds. Compassion runs deep in their heart, and that's just the kind of spirit needed when a new Pokemon needs healing of a special kind.
Type Null-
He was thought of in a lab. He was born in a lab. He refused to die in one, too. What felt like an eternity ended in one night.
Null escaped the Aether lab with many scars, on the inside and out. Not knowing whether he'd die to the sea, he woke up in a strange house, around even stranger humans; Ones he had never seen before. They didn't talk like the ones in Aether, or dressed like them.
Trust is a long way away, but maybe he can start here, with these humans.