NOTE: I know this is the second edit I’ve done involving Rarity being hypnotized by an offscreen Sci-Twi. Please bear with me as it is the only way I could make this scenario work.
 
Rarity has spent the entire day combing the sands of Canterlot Beach in her search for her missing custom, one-of-a-kind earring. She ends up dragging Applejack and Rainbow Dash (who were relaxing nearby) along for the search, but as the day drags on, and the girls continue to not find the earring, it becomes apparent that that Applejack and Rainbow are becoming tired and irritable. Time and time again, they try to talk Rarity out of her search, telling her that one missing earring is not that big of a deal and that she can always make another one. However, the fashionista refuses to back down from her quest and continues to push her friends to look, even though they are very tired, hungry, and irritable. Eventually, Rarity decides to head off on her own and begrudgingly allows her friends to take a break. Knowing that the poor girl is going to exhaust herself with her obsession, Rainbow and Applejack begin to think up ways to get her to back down and just relax. Luckily, Rainbow spots Twilight Sparkle reading a book nearby and (upon remembering what Twilight said she would be studying that summer) begins to think up a plan and tells Applejack to set up a beach blanket and umbrella over where Rarity is presently searching….
 
A little while later, Rarity is continuing her search for her earring on her own when she is suddenly approached by Twilight, who is holding a shiny gold pocket watch in her right hand. After the two exchange pleasantries, Twilight tells her purple-haired friend that she wants to show her the pocket watch that she got from her grandfather last week. Despite wanting to get back to finding her earring, Rarity agrees to have a look. What she doesn’t know, however, is that she is actually falling for a trap set up by Rainbow Dash in order to get her to stop looking for her earring. Levitating the pocket watch with her geode powers, Twilight begins to swing it back and forth in front of Rarity’s eyes, which confuses the fashionista as she thought she was just going to look at it. However, as her gaze becomes locked on the watch and she begins to hear Twilight tell her to relax, Rarity finds herself slipping in to a deep state of hypnosis. Her eyes begin to droop, her now limp arms begin hanging in front of her, a relaxed smile tugs at her lips, she starts to slouch forward, and she is left with a strange yet alluring desire to do whatever Twilight tells her. Seeing that her friend is becoming relaxed and sleepy, Twilight tells Rarity that she can close her eyes and listen to her voice, which the purple-haired girl does.
 
Once that is done, Twilight begins to give Rarity the suggestion Rainbow Dash came up with: instead of looking for her earring, all Rarity wants to do is go over where Applejack has set up a blanket and umbrella, lie down, and go to sleep for a while, not waking up until she hears one of her friends whispers the phrase ‘Aquamarine’ into her ear. After Rarity confirms that she has taken in the suggestion with a drowsy nod, Twilight ends the impromptu hypnosis session with a finger snap. Almost instantly, Rarity (eyes still closed) walks over to the blanket and umbrella, where Applejack and Rainbow Dash are waiting and watching. After discarding her headset on the ground, Rarity slips out of her sandals, lays down on her side on the blanket, and begins to give a few light snores, indicating that she has truly fallen asleep. Twilight soon walks over to join the group and Rainbow Dash thanks her for her help. Twilight says it was no big deal, as it gave her a chance to test out some of the hypnosis skills she’s been learning over the summer. The two girls then walk off to get something from the snack shack, but Applejack chooses to hang back Rarity as she snoozes in the sunlight, figuring someone should be there to not only wake her up eventually, but also explain what was done to her and why….