First of all you have to know that the current game I‘m doing wasn‘t my first game attempt.
I‘ve tried myself on a more rpg-based fetish game with monster & boss fights as well as an ongoing story. The plan was to release it chapter after chapter with new parts of the map following our heroes. These would have been what I call the ‚unicorn squad‘ – containing Twilight, Sunset, Starlight and Trixie. It would have taking in a remote, magical world (A banished place)
which would only be accessible through some ancient portal in some woods. Their job would been to free that world of an ‚dark, evil force‘ that conquered the land hundreds of years ago.
Quite towards the ending of the game they would have had to get two fragments to open a huge gate to face the end-boss. To do so they would have fought against a dragon to the south (the lava/fire level of the game) to get the first fragment. For the second their job would have bern to head to the north to face the ‚Empress‘ – ‚Queen Frostfire, Empress of the frozen north‘ in a frozen palace up on a high, snowy mountain.
That fight would have been a bit special because usually out heroes would have gotten limitless tickles if lost to a boss. In that case they wouldn‘t. You only would have gotten a tickling scene once you win!
So far to the game idea behind it.
Now to the character in question.
Frostfire used to be kind ruler to the kind of ‚Frozen Ponies‘.
One day however – when the ‚dark, evil force‘ conquered the entire country, a shattering rumble would have gone through the entire country.
That caused an icicle to fall from the ceiling of Frostys castle – hitting her horn and splitting it in half.
The immeasurable pain that came with that changed her. It didn‘t just split her horn, but also her personality in two. She turned into a schizophrenic ruler, with a kind, bright side (that quickly vanished) and an aggressive, evil one. She quickly turned into an evil Empress, freezing and in some cases even ‚killing‘ (by melting the frozen ponies) her own subjects.
Ever since she‘s been living in loneliness inside her frozen palace.
Until Twi and her friends showed up.
When they won they would have done what all the creatures did to them before in the entire game. Trapping the beaten alicorn to her own throne and tickling the shit outta her.
To their surprise that changed her. Her aggressive, evil demeanor vanished – and the old, kind Frostfire finally returned – saved through mere tickling, because at that point that would have been the only positive, happy source that would turn her back to good.
The end of her story would basically be: She‘d live in Twilight‘s castle so she can finally make some friends, better herself and wouldn‘t turn back to her darker side.
She‘d easily get triggered tho. But at this point they‘s already know how to stop her madness from turning her evil again – by some simple poking her ticklish spots.
Her magic also isn‘t that useful anymore. More filigree spells (even stuff like levitation of objects) wouldn‘t be possible – the broken horn is just to damaged to do such specific tasks anymore. Instead her frost or (blue-)fire magic would only be chaotic and destructive (so you could still use her as a weapon – as long as collateral damage is ok)