This Irish connection for the Fears family intrigues me. My research to date seems to point to an English origin for the family in the area surrounding the village of Chew Magna on the River Chew in Somerset County, England. The church records there include reference to a John Fear and his wife Agnes that had their son Thomas Fear christened in 1644. Thomas then turns up in Virginia in 1657 as an indentured servant to one Thomas Graves.
With that in mind, however, there exists a Fears family Bible record (in Jasper Co., Georgia) that begins with one William Fears, born about 1720 in Ireland that married Francis Sadler, an English lady. Many Fears researchers have chalked that entry up to misunderstanding or mistake, but might there be some truth to William's Irish birth? It seems odd to find a mistake of that sort in family Bible.
Anyway, I'd be interested in your thoughts on this. Do you know the county in Ireland from whence came your Agnes Fears? Perhaps a thorough search of the Irish records in that county would turn up something useful. Just thinking out loud ...
P.S. Gordie Fears and I both have our DNA results posted at Ancestry.com. Perhaps there are descendants of the South Carolina family that could have their DNA tested as well.