The word riddled means 'full of a particular thing', 'infested', or 'pervaded'. Some synonyms for riddled might be 'saturated', 'infused', or 'permeated'. Another word that could be used is 'teeming', which implies a surplus of something. If something is riddled with something else, it might also be described as 'laced', 'interwoven', or 'intermixed'. For a more dramatic descriptor, 'besieged', 'plagued', or 'overrun' could also work. Using different synonyms can add variety and nuance to writing, helping to avoid repetition and elevate the richness of language.