It was basically the most awesome morning Fionna remembered having had in any recent memory. She had woken up very early, feeling brisk, well-rested, and head full of ideas and desire for adventure. The weather was perfect, not a cloud in the sky, just the right temperature, and with a little bit of wind to further cheer them. Finally, Flame Prince had come over early to hang out, and they had spent a couple hours just making plans for the rest of the day, because this kind of a day required some planning to get the best out of it.

The final list took more than two thirds of the length of this first chapter of the fanfiction, and neither of them thought it was in any way unreasonable:

- Go to the Breakfast Kingdom, fight random encounters
- Breakfast with the Breakfast Prince
- Rescue the Breakfast Prince from the Ice Queen
- Chase her away, shouting about how "we will meet again!"
- Prepare for the next meeting
- Fight random encounters and help the helpless on the way to Lord Monochromicorn's place
- Pick up Cake and Lord Monochromicorn for further adventures, subtly and tactly refrain from inquiring what they did last night
- Ask them about the "tiers" on the way to the Lumpy Space
- Hang out at Lumpy Space for a while, save Cake from being turned into a Lumpy Cake
- Storm is coming! Spend exactly eleven minutes fighting the storm elementals and negotiating with them about coming back tomorrow instead: today is way too perfect for rain and stuff
- Pop by a store to buy some umbrellas to prepare for tomorrow
- Consider hanging out at the Marshall Lee for a while
- Decide against it because Marshall Lee is a jerk and no one in their right mind would want anything to do with him
- Go hang out with Prince Gumball instead: he's so much more awesome and has a lot of inventions to show
- Ask him about what's his story with Marshall Lee, try to get them to reconcile for whatever it was
- Fail miserably on both counts
- Go hang out with Tree Trunks with Mustache and Bow Tie (Male), have apple pie for lunch
- Rescue Wildberry Prince from the Ice Queen
- Deal with Magic Maid being a jerk, make her dispel the curses she put up
- Go to Mars and learn Magic Maid's history from Mary Todd Lincoln
- Be sad
- Investigate the mysterious blue box that just showed up from nowhere on the countryside
- Learn it's bigger from the inside, have a crossover adventure with the strange alien lady that lives in it, learn from her about the history of Aaa and humankind
- Defeat surprisingly threatening pepperpot creatures
- Go watch the sunset atop the clouds, have a romantic moment, have the moment be killed when Cake's phone rings
- Bail out Cake Jr. from prison, lecture him about why crime is wrong
- Check out the Couples Only Movies Night
- Consider kissing Flame Prince, remember how the last time turned up
- Just hold his hand instead (remember tinfoil!)
- Have a romantic candlelight dinner, eat pasta
- Shoo the Flame Queen from the candle
- Watch the stars for a while, find patterns in the constellations, think about life
- Try to not think about being the last human on Aaa, though
- Find a mysterious portal to another universe
- Go through, have a crossover adventure with the Avatar and her friends
- Foil the plans of the Ice Queen and the Fire Lady, who had joined forces
- Make friends, eventually bid tearful farewell and go back to Aaa
- Take Flame Prince and Lord Monochromicorn home
- Go home, talk with Cake about how awesome day that was
- Sleep
- (Optional: if anything else shows up during the day, adjust plans and add that thing in)

It was, indeed, truly the best plan ever for the best day ever. It took several pages and was very scientific and therefore legitimate.

"This is going to be so awesome!", Fionna said. "It will be the best day, and end up as the most awesome piece of fanfiction ever written!"

Then she heard the faint clank from upstairs. "Huh? That sounded like the window opening... I should probably go check it out before we leave?", she asked the Flame Prince, who just shrugged.

It would take her only ten seconds, and in no way derail anything else they had planned for the day... but it would still be kind of inconvenient and make a bit of a chink in the diamond of the perfect day. Would she take that ten seconds, or would they leave immediately?