>>42393930
Tunafics are often like that, this one probably the most as Luna Cyberprincesses around, but doesn't spend that much time with Twilight:
https://www.fimfiction.net/story/246579/luna-princess-of-space
Twilight takes the student role https://www.fimfiction.net/story/63121/archmage
This is a great story, and more down to Equestria than those two:
https://www.fimfiction.net/story/247622/twilight-good-night
Not hyperintellectualism, just the two of them going through Luna's past and present princess problems.

And, of course, there's more like >>42377114 and https://www.fimfiction.net/story/459048/natural-ones

Cuori Intrecciati's opening scenes also has a lot of that, but it's mostly not a Twilight romance fic.