Answer:
Friendly
Prefix <u><em>A: Fee</em></u>
Root <u><em>A: Friend </em></u>
Suffix <u><em>A: "not harmful" or "suitable for"</em></u>
Definition <u><em>A: kind and pleasant.</em></u>
Archenemy
Prefix <u><em>A: Arch</em></u>
Root <u><em>A: Arch</em></u>
Suffix <u><em>A: Arch </em></u>
Definition <u><em>A: A person who is extremely hostile or opposed to someone or something.
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I don't really know the first three are kinda weird but these were the answers i got.