Well, we all know what the word "Fort" indicates.
Now the word "Fiend" ---
Main Entry: fiend
Pronunciation: \ˈfēnd\
Function: noun
Etymology: Middle English, from Old English fīend; akin to Old High German fīant enemy, Sanskrit pīyati he reviles, blames
Date: before 12th century
1 a: devil 1 b: demon c: a person of great wickedness or maliciousness
2: a person extremely devoted to a pursuit or study : fanatic <a golf fiend>
3: addict 1 <a dope fiend>
4: wizard 3 <a fiend at mathematics>