At Weathertop, did the Nazgul fear Frodo?

[Eldar14]

Back to the original question, I think they did actually fear him to some extant. Well, it was actually more of a fear of what he could become. That is why they wished so much to kill him. If Frodo had held the ring, he would have become a slave of the ring. However, he would be more powerful, powerful enough to control any Nazgul or all Nazgul. If they had not feared him, they would have acted less aprehensive.