Follower AI are a pretty interesting feature (There's a "basic" example on Return of the Hylian SE), but making a AI like you described require a very long time to do, basically, the follower has to constantly analyse what surrounds him, the script has to determine it's path, when he should attack, when he should defend himself, this is probably one kind of a script that would take weeks to make, but, this could be interesting, I already planned things like that for some boss battle so it is on my todo list as well