ita Numitori Albana re permissa Romulum Remumque cupido cepit in iis locis ubi expositi ubique educati erant urbis condendae.
In particular, what is the subject of "cepit"? Though I get the gist of it on my own, I've cheated and looked at a translation, which translates "cepit" into English as passive, and Romulus and Remus as the subjects of the sentence. Clearly, cepit is active, perfect, 3rd singular, and the boys are accusative, right? Is there some idiom with "capio" that I'm missing? Usually, with a missing subject, there's a he/she/it that can be inferred, but that doesn't seem to work here.