[Pre-time skip, nothing spoilery in this chapter]
"So you were given these by a strange red haired woman in the market?" Edelgard looks a nervously twitching Bernadette in the eye as she holds up a rack of crystal vials containing a deep purple liquid
"Sshe was a merchant, I bought them from her when she said they'd grant my u-u-u-ltimate desire" the archer stutters, the future Empress's laser focus on her not helping her usual anxiety in fact making it worse.
"Your ultimate desire yes?" Edelgard hums, switching gaze from the noble to the vials, to Berni's relief, the girl nearly collapsing where she currently stands "These will be of valuable use to the Black Eagles, I'll keep them in my room and we can show them to the professor after our next class" she states, turning her head so the younger girl doesn't see her blush, in turn not seeing Bernadette's pink cheeks as link most of the other women in the monastery there was some level of infatuation towards the newest professor Byleth, who seemed to see through all their defences with a single glance of his eyes
"Y-you're right Edelgard, best you bring it to the professor" Berni nods, tapping her fingers together "Do you know what it will grant you?"
Edelgard smirks "I think I do, but we'll find out by the end of the week" the archer nods, leaving the other girl to hide in her room,
That evening Edelgard sat on her bed, her mind drifting to the vials Bernadette was given, as well as the desire it would grant them all, she would be able to stop Rhea and free them from Seiro's grasp, she just had to take the chance. Skipping the plan of checking with the professor she pops open one of the vials and downs it, the liquid watery and sweet. and she smiles, before her head throbs and she passes out onto the bed.
Groaning Edelgard awakens the next morning to see things were very wrong indeed: she was sitting on her bed, but the entire room was huge... no she was little, maybe about 3-4 inches tall. How was this her ultimate desire?
What the royal didn't know was Anna didn't give Bernadette vials that grant desires, but that grant HER greatest desire, to be unnoticed and able to remain hidden, in this case through shrinking. Details are important with things like this.
Edelgard tried focus her mind, trying to figure out how to deal with this, when her door opens.
Who was it?
Byleth, checking up on his favourite students?
Bernadette, making sure the plan was still going on?
Someone else?