ooh, i like this. alot of ways to go about it though
to make navi follow link in a fairy fashion, pin it rope style to link when on contact, make an animation of her fluttering to boost this effect.
i would probably suggest working out a targeting system like the z targeting in Oot
once a unit is "targeted" un pin Navi and activate her (how you do this is up to you) 8direction/pathfinding/bullet
to fly to the enemy (give her VERY high speed).
again, when she reaches the enemy (on collision) pin it to the enemy, and have a new animation where she goes red and fly's around angrily. actually i think that was only when she targeted Sakon the thief
then when targeting is off, or the enemy is dead, or as an else clause have navi pathfind back to link, and again on collision pin
if you don't want the z targetting, you could just have a boolean if the los from link is true or not for each enemy.
to decide which enemy she fly's too is a bit more complicated.. you could just pick an instance where the boolean is set... i'm struggling with the pick nearest/furthest event personally, so wouldn't try telling you to do it, just doesn't seem to do anything
if you struggle still, write me back and i'll try to code it.
i write this as i'm very lazy at following links and don't like downloading things (sorry Majin Buu)
rex plugin moveto will help you a lot.