I exemplify with the following, but I ask this in general. How can I learn more about affixes that change meaning, especially those that are 'upended into' their antonyms?
For example, I was researching the etymology of surreptitious:
surreptitious (adj.)
mid-15c., from Latin surrepticius "stolen, furtive, clandestine," from surreptus, past participle of surripere "seize secretly, take away, steal, plagiarize," from assimilated form of sub "from under" (hence, "secretly;" see sub-) + rapere "to snatch" (see rapid).
How did the sub- prefix invert to its antonym sur- (French for 'on')?
Yet (to my surprise), 'subreption {noun}' maintained the sub- prefix.