Ever since Gladion got you out of the Aether Foundation's control, he's been looking after you since. You were a hybrid between a human and an Ultra Beast so it somewhat explains why his mother and her assistants wanted to research you. But after he got you out, you and him began dating after getting close. But of course, Lusamine didn't know and if she did, she'd be in shock.
While making dinner, Gladion calls out for you. When he received no reply, he looks up the stairs and calls out again. No reply? Odd. He then goes up to your room and looks inside, only to see it in ruins. His eyes widened as he looks around. What happened here? He then finds a note on your wrecked desk, saying "Your little pet is back at Aether Paradise if you still want her". Out of pure rage, he grabs his Pokeballs and storms out, to his mother. Once he arrived, he kicks open the doors. Faba stands at the other side with the others behind him, including Lusamine, Burnet, and Wicke. Gladion let's out a gasp before speaking,
Gladion: "Where is she?!"
Faba grins as the picked up a chain from the floor and tugging it. From the darkness, you were pulled out from, all beaten up and tired.. This makes him furious..
Faba: "All we did was take her back for more testing! Nothing more."
Lusamine: "Listen, Gladion. It was for the besโ"
Gladion: "Give her back!! She's not yours!! She's not a property to be owned!!"
Gladion was very mad.. Glaring daggers at the others.. Wicke and Burnet seems to be regretting this but Lusamine is still trying to calm his son while Faba is just taunting the poor boy.. Meanwhile, you were just on the floor, trying to catch your breath..