Fearing adverbs are provided in this article. The words listed here are commonly found along with the verb fearing in sentences. This reference page helps answer the question what are some adverbs that describe or modify the verb FEARING.
apparently
evidently
greatly
justly
probably
Hope this word list had the fearing adverb you were looking for. In addition to adverbs used with fearing, other example verb adverb pairings can be found on this site.
You can help by adding more adverbs in the comments. Thanks.