Does anyone know what the relationship is of specific OE prepositions with nominal cases? I'm trying to write a story in OE and I need to know. Right now, I'm just using German as an analogue since I'm familiar with that. An

Old English has a small number of prepositions which are "two-way" in the same manner as found in German: binnan, bufan, in, innan, ofer, on, under. Most of the others primarily take dative objects but may also govern accusative or instrumental; a few are attested with every possible case except for nominative. Which is to say that, overall, there's a great deal of variation, so for your purposes the choice of case probably doesn't matter too much.

Reading your post reminded me of an Old English website I came across 7 years ago that listed a bunch of prepositions and the nominal case associated with each one. Some prepositions take both dative and accusative, depending on the context. See: http://www.wmich.edu/medieval/resources ... nprep.html

Scroll down to section 10.5 (Prepositions).

Hope this helps!