fowl

could there be an NPC type, or types, that, when link gets close to it, it flies away? like, it walks around normally, using it's own tiles, and when link gets close, it flies in the opposite direction that Link is moving? there could be 7 types, fly left, right, north, south, right/left, northsouth, and opposite. each one should be obvious as to what it would do

the only think I can think of that would make this hard, is the trigger for making them fly away

I like that idea! Here's some others:
1) Retreat: Stands still until link gets near it, then it walks offscreen completely via the nearest edge.
2) Patrol: These walk in a pattern, such as left and right, continuously. It turns around when it hits a solid combo, or perhaps a "No NPC" flag or combo type. Can have left/right, and up/down. (Basically, similar to the movement patterns of trap-left/right and trap-up/down, except they dont hurt you & they move very slowly)
3) Retreat Underground-Still: Stays in same spot but when link gets close to it, its animation changes so that it "digs" and hides underground (kinda like leevers)
4) Retreat Underground-Move: Like the above, except it actually walks around and then retreats underground when link gets near it.
5) Fly: Simply an NPC that flies around the screen, kinda like a keese--would be good for butterflies and other flying "animals" and stuff--perhaps two types: fast, and slow.