Do you have any game based headcannons for you team or trainer?

Just caught Solgaleo in Ultra Sun, Lillie asked me to keep it and Necrozma together since Necrozma is absorbing light because of it's constant pain, and just being near Solgaleo and my Z-crystals soothes it. I get the head canon since I can fuse them, that after finding out the story, your legendary voluntarily allows you to fuse it with Necrozma, and as thanks, Necrozma leaves the legendary in control of their fusion,