What if CoW!Dragonborn started going just a little bit insane after Arniel's Endeavour
One day out of the blue, they start asking the students and staff about a person called "Arniel," supposedly a former colleague of theirs, no one really knows who they're talking about.
Seems to have suddenly gained an uncanny understanding of Dwemeris, more than any normal scholar's understanding of the dead language
Sometime takes weird turns and walks into trees whenever they're in Cyrodiil, almost as if the landscape they're seeing is... different from everyone else's
Starts seeing beasts that aren't there. Riekr with faces like men, flying sea creatures, baboon-like trolls and things that are like-trolls-but-not
Belly-laughs at things that aren't that funny, like a sword in a campfire, a frozen man stuck hanging from the ceiling, or a random assortment of cheese on a shelf.
Freaks out their party members sometimes by humming things, songs they haven't heard before but still somehow sound eerily familiar.