Feral cats, like house cats, each of their own personalities. Some tame quickly, some with time, and some never. We manage feral colonies and have gained trust with some of ours, but it has taken time. The best way is through food. You need to feed every day in the same place and the same time. Never force the issue but let the cat come on its own. Also try giving it special treats like chicken or tuna. Trapping and getting the cat fixed will help calm it down some. Good luck with this!