I have been looking for some and have come empty handed. There are a bunch of Human Flash with Princes Twilight or Pegasus Flash with Princess Twilight but i havent found any were is the human Twilight except for one with a mock/pitty date.

5877161 while this has the regular Twilight tag, it's basically the Sci-Twi one

Story

5877171 I read it a little while ago. Wish it actually had some better development for the relationship.

5880582
There is one called Power Rangers: Guardians of Harmony. The author supports FlashLight, and in the story Flash and Sci-Twi slowly develop a friendship that will probably blossom into romance. There is one chapter where the two need to go undercover to a gala together by acting as a couple.

5978420 Thanks. Just that i have been reading that one up till date.

5978431
I just remembered that the author MaggiesHeartLove also has two stories where Flash and Sci-Twi are together. See her adaptations of Friendship Games and Legend of Everfree.

5978707 I just read them. Thanks. I have to say i really liked those stories, the author gave good interactions between the two and had good development, the bad thing is that their moments were overshadowed by plot and other characters.

5983361
You're welcome. Glad you enjoyed them. I have two other stories in mind that might be what you're looking for two.
1. On deviantart there is a story called The Magic of Love with this pairing. But it doesn't update much due to writer's block from the author. She does say once the next chapter is out they might be more frequent.
2. There is a story called Persona EG where Flash and Twilight get together but it might not completely qualify as FlashxSciTwi because the Twilight in the story is fully human but has the appearance and (mostly) personality of Princess Twilight. I think it is one of the best stories on this site, but it often experiences long hiatus periods, which can be pure torture when you want to know what happens next.

5983639 I have talked with the author of magic of love(it's also on fanfiction). I have read the persona one and well is just basacly Princess Twilight if the pony world didn't exist. The author has some similar to those like the yugioh one.

Sci-Twi is really a special case with it comes to the human counterparts of the mane 6. I say this because unlike the other 5 while despite having some diferent likes they feel the same as their pony counterparts but Sci-Twi feels like her own character without depending so much of Princess Twilight personality