Here’s a classic trope I haven’t seen in the Frozen fandom yet: the love potion. I’m using the canon-verse for this plot. Oh, and remember, I said I haven’t seen it used, not no one has ever used it. If there’s a fic out there that does use it, I don’t know about it.
Someone (unscrupulous visiting noble, perhaps) manages to slip a love potion into Elsa’s drink by bribing a guard or staff member. He could even manage to do it himself if he’s attending a small event hosted by the queen (it can’t be that large, though, as the chances of it misfiring is too high the more people are around). She drinks and he goes in for the kill, only for Anna to inadvertently intercept Elsa before he can. He is enraged but manages to stifle his reaction, thinking at the very least, the sight of the Queen of Arendelle trying to intimately embrace her own sister will be quite the sight. Imagine his dismay when nothing happens. He is furious and leaves early, thinking of all the gold he wasted on a useless potion, never knowing that the potion works, but had no effect in this case as Elsa is already in love with Anna.
longer variant: Elsa drinks, but before she can turn her head to look at her attacker, Anna suddenly appears behind her and covers her eyes with her hands. Before Elsa can say anything, Anna takes over, ordering the guards to arrest the noble. She fiercely whispers into Elsa’s ear to trust her, let her do this, Elsa is in grave danger, and please, whatever you do, do not open your eyes. The urgency in Anna’s voice borders on panic, and Elsa commands the guards to obey their Princess, correctly surmising that some may be hesitating to follow Anna’s orders since the both of them are present. The noble is arrested while Anna manages to escort Elsa from the room.
Outside, Anna uses a strip of material to blindfold Elsa. She explains that she was running late to the small event and found a scrap of paper in the hall. Curious, she picked it up and read it, discovering it to be instructions on how to use the love potion. The potion takes effect in a quarter hour, making the person who drinks it fall desperately in love with the first person to make eye contact with the victim. Not knowing how much time she had but knowing Elsa was the target, she charged into the room, and seeing the visiting dignitary staring at Elsa, knew immediately who was responsible.
Elsa is confined to her room, always blindfolded to prevent any accidents. Anna scours the library to find anything she can about love potions. Kristoff is sent to consult the trolls. The guards question the dignitary. The answers come back: if triggered, most potions of this sort wear off after several days, leaving the victim to suffer the consequences of her actions. The magic in the potion is quite potent, though, meaning in order to not trigger it, Elsa would have to remain blindfolded for weeks. However, the noble paid dearly for a much more powerful version, increasing the length of time Elsa would remain sightless. It could be months before the magic fades.
That night, it is just Anna and Elsa present in the latter’s bedroom. Anna bounces between despairing at the situation and raging at the noble who tried to capture Elsa and, by extension, the kingdom. Elsa has been quiet since the news but now, asks for Anna to sit with her. The pair clasp hands. Elsa asks if Anna trusts her. Of course, is the reply. Elsa asks again, her voice serious. Anna says yes again. Elsa has a way to break the magic but needs Anna to stay still and trust her. Anna agrees.
Slowly, Elsa releases one hand from Anna’s and reaches behind her head to the knot holding the blindfold snug against her eyes. She pauses at Anna’s sharp intake of breath, then continues when Anna squeezes her hand. The blindfold falls away. Elsa slowly opens her eyes, blinking in the dim light of the room. After several moments, she lifts her head and gazes into Anna’s eyes. After several seconds of the tensest silence anyone can endure, Elsa closes her eyes again, breaking eye contact. She squeezes Anna’s hands and thanks her for trusting her.
Anna is confused. She wonders aloud if the potion was a dud. Elsa replies it wasn’t. She could feel the magic coursing through her veins, can still feel it now. Anna admits that she was expecting Elsa to lunge forward to kiss her. She asks if its because Elsa loves her as a sibling, maybe that was stronger than the potion. Elsa shakes her head. It’s because she already has lots of practice suppressing her urges. The love potion wouldn’t change anything.
The pair fall silent again. Elsa pulls her hands away and closes her eyes. She draws into herself, and apologizes. She understands if Anna wishes to leave, if Anna hates her, if she never wanted to speak to Elsa again. She always thought of herself as a monster before, thanks to her magic. Now, she has a new reason. Before she can continue down that path of self-destructive thinking, Anna shifts and cups Elsa’s face in her hands. Elsa is startled and opens her eyes to see Anna looking at her with such affection. There are tears in her eyes, but before Elsa can do anything, Anna leans forward and kisses her softly.
After an eternity of sheer perfection, the two separate. Elsa asks how long. Anna says it feels like it’s always been there, in the background, but she never really thought about it until after she and Kristoff broke things off. Anna asks how long? Elsa replies, since before the coronation. Anna ponders that, then makes a comment if she had any idea it would lead to a confession, she would’ve gotten Elsa a love potion months ago. Elsa looks aghast at Anna before noticing the cheeky grin. She grins herself and the two laugh.