So I have it on authority that a new ship called Canyinn is a thing now; I don't know if its canon or not, but I ship Canyon and Finn like crazy now! So here is the first of probably more fics, addressing the obligatory Fubblegum interpretation as well.
Disclaimer: I do not own Adventure Time or make profit from this fanfiction. Additionally, I haven't actually seen Billy's Bucket List as of writing this, so I do not know how canon compliant this story is.
Princess Bubblegum loves Finn.
She's loved him for a very long time.
Long enough to know that she cannot have him, cannot be with him, can't hold hands with him and watch dumb movies with him and dwell in his home and kill nasty things with him. Not the way things are.
She has a kingdom to rule, much as she wishes she didn't these days. She has thousands of lives to care for, their happiness to ensure. Her own happiness is irrelevant, and the happiness of those she loves romantically. She simply cannot afford to let that go; it would be a shameful surrender, giving in to weakness like that.
So when she heard that Finn had a girlfriend all those years ago, she was enticed, excited; Finn would be loved and be safe, and things would be okay. And then it was Flame Princess, and things got worse, things got out of control, and Finn came out of that even more wounded than before.
What Finn needed, Bubblegum had decided, was a heroine. A woman, more experienced and wise than him, to teach him of the proper ways and care for him as he flowered into proper manhood. To do the things she couldn't, and do what she wanted in her stead.
Bubblegum didn't like it, but what she wanted had never really mattered.
As long as Finn was happy, and whoever was with him cared for him and met her own approval, than Bubblegum would be...
Hah. She wouldn't be happy, not a bit, but she would be satisfied, and a bit of her life would close off, gone forever, and be at last safe.
And Princess Bubblegum hears things. She knows things.
Whispers on the wind, rumors tracking through her spy networks.
When she hears of a woman, a giant woman named Canyon, associating with Finn in a rather intimate fashion, she is intrigued.
She's all the more when Canyon herself requests an audience.
And Bubblegum sees the future, sees the trends flow together, the dictates of what can be making sense at last.
She sees her future. It hurts, and she accepts it.
Here and now, bright and loud, clear as the sun through parting clouds, The horns blow again as the heroine steps through the door.
Princess Bubblegum's kingdom is that of one of the cultural hubs of Ooo, and many beings of many shapes and sizes have passed through her realm in the past, and accordingly its doors are made for those of many different shapes and sizes. And even so, the towering form of Canyon the giant ducks down nearly double to fit in through the doors.
Somehow, to her credit, she manages this with a modicum of grace and dignity. It's a bit lessened when she turns sideways, almost tripping on the carpet, and a harsh tearing sound where a heel meets the floor and shreds the carpeting gives Bubblegum cause to wince.
Canyon catches herself, stomps the floor for balance (leaving a faint imprint of her foot as well) and wavers. A few gumdrop people take steps back as though in sudden terror of her high body falling down upon them, and Bubblegum imagines the impact with gritted teeth.
But it does not come, thankfully. Canyon the giant steadies herself fully. She breathes in, breathes out, and Bubblegum has seen something of that before. In this, she sees an echo of herself, desperately trying not to make a fool of herself. Bubblegum says, "You are well met, Canyon of the Grasslands."
Canyon looks at her. The calm, almost placid face (for the blue giants are known for their almost too serious faces; old legends says they were born of the mountains, the many-times removed children of the frost giants of mythical Jotunheim and the very rock of its universe-spanning mountains, and they certainly look stony enough) shifts like an avalanche in motion, and her expression is grateful.
"Princess Bubblegum," Canyon speaks, and she bends down low , one knee to the carpet, lowering her shoulders so that she could fit into the room. Her hair dipped to the carpet, a splash of contrast against the pink (and didn't blue just go so well with pink). "I ask of you permission in your formal capacity, I ask you a boon and for your blessing."
Princess Bubblegum nodded. "Proceed."
Canyon steels herself. Carefully, picking each with steady thought, she says, "I ask for your permission to court Finn the human boy, and your blessing in caring for him."
Just for a moment, long enough to draw attention even from her notoriously unfocused people (even James, who hangs around the castle a lot these days, gives his Princess a curious look), Princess Bubblegum freezes, goes brittle, a hint of steel beneath the silk.
Bubblegum says, carefully, "You wish to court him in full honestly?"
Canyon nodded. "I do. I most sincerely do."
Bubblegum nodded. "I... I see."There is a long pause. Longer, to those who know her well. Eyes turn towards the princess, and murmurs move, and the worst-kept secret of the Candy Kingdom is how shamelessly and openly in love with Finn their champion she is. And she does not pursue him, cannot pursue him, and this is a shame and a pain she bears openly, bitterly. Everyone knows it, and many outside the kingdom.
Canyon might well know it too. Asking for the hand of the one she cannot love, asking her permission to love him... murmurs rise up in the candy people, asking whether this is a ill omen or a sign of virtue.
Princess bubblegum breathes in, breathes out.
She says, "You speak honestly and sincerely." She raises her feels like forever, like casting chains around herself, burying herself in lead and throwing herself into the sea to drown and dissolve.
But, all the same, she 's surprising, even to her and to Canyon, that she can suppress the tears, and the bitterness, and that too is smoothed away by the thoughtfulness of the request. "I... I thank you, for coming to me," Bubblegum said. "I grant you my blessing, my good wishes, and I ask that you care well for him."
Canyon nodded. "I promise that."Bubblegum nods again, and the rest of her body is rock-still.
Later, if Canyon happens upon her and offers a hand to hold her while Bubblegum lets herself cry, neither of them speak of it.