Here's some info about Dawnlite and Spotlite. Some of this ties in with the backstory. In addition, despite being evolved Pokemon, both Dawnlite and Spotlite are cubs.
Dawnlite's mother (likely an Espeon) had a strange quirk that ran in her family, in which their offspring was guaranteed to be shiny (or so they thought.) Both of Dawnlite's parents wanted to take care of a shiny male Eevee, but were surprised when there were two eggs. They wanted a complete surprise, which is why the Espeon didn't use psychic powers. The first egg to hatch was Spotlite, which made Dawnlite's parents panic as she was female and NOT a shiny, so they abandoned her with the other egg, which ended up hatching not even a minute after Spotlite was abandoned. That egg ended up hatching Dawnlite.
Shortly after Dawnlite hatched, him and his parents were noticed by scientists who were overseas, and kidnapped and taken to a science lab in a "top secret location" out of the country. Once Dawnlite was in captivity, the last thing his parents had told him was that they were so lucky they hatched a male and shiny Eevee, and they never mentioned Spotlite. The last thing Dawnlite saw was them being taken to an execution room, where they were injected with acid to die slowly in agony.
Later on, Dawnlite was put with Skurry who was less than a week old at the time, but seemed to have a friendly relationship with Foxy who was born on the exact same day. Skurry would almost always mistreat him, simply because Dawnlite wasn't his "real brother", and this would cause Dawnlite to be constantly depressed and almost always crying. To make things worse, Skurry would often wait until Dawnlite falls asleep, and then drag him to a crate without waking him up. From there, he would sit on the crate which had a convenient hole at the top, and then slouch to that if he were to fall asleep, his butt would prevent airflow into the crate. As a result, Dawnlite would suffer every night by being trapped in a box with Skurry being gassy and on top of it. Eventually, Gunter broke into the lab to rescue the animals, he took Dawnlite, Skurry, and Foxy with him and smuggled them back into the country. The rest of the animals might have been rescued by Chaos. He then offered a place to stay for Skurry, Foxy, and Dawnlite, which was originally intended for him to use as a vacation house. Skurry and Foxy stayed there, but Dawnlite seemingly wanted to stay with Gunter and gave him a sad puppy-eyes look. Gunter thought nothing of it and took Dawnlite to an alleyway where he was staying. Upon entering the city, Dawnlite had bad memories because it was the same city where he was kidnapped. He would wake up as an Umbreon the next day.
Gunter eventually sent Dawnlite back to Skurry because his sister nearly killed Dawnlite by wanting to dress him up as a mummy, then proceeded to wrap him in black Duct Tape and throw him in a dumpster. Gunter got home early and Dawnlite wouldn't have made it if that wasn't the case. Gunter also took a DNA sample of Dawnlite to see if there was anything different with Dawnlite and a normal Pokemon, because of Dawnlite's family being shinies.
Spotlite eventually came across Gunter as mentioned in her backstory. Since Gunter had Dawnlite's DNA sample, he managed to test her DNA, which confirmed she was his biological sister. This surprised Gunter, as Dawnlite never mentioned any siblings.
Both Dawnlite and Spotlite have some unique power.
Dawnlite's ring and eye colors can determine his mood. Normally, his rings are blue and eyes are red. If he's sad, his eyes will turn blue. If he's angry, his rings will turn red. If he's feeling both sad and angry, then it'll be a combination. Additionally, Spotlite can de-evolve back to an Eevee and switch to another evolution. However, if she does switch, she'll have trouble maintaining her form. When she goes to sleep, she will wake up as a Sylveon if she had been asleep for half an hour or more.
