Theres a few approaches to AI you can take...
One approach is to make the computer controlled character react to stimulus with pre-scripted actions. For example, have the computer react to being hit by running away.
Another is to have the computer "remember" how they've been treated by you and react to you accordingly.
Or you could just use random numbers to generate behaviour. (Although - the computer would seem to react to actions randomly and stupidly)
I think that a good starting point for any AI is to setup the functions which enable the computer to do things. What I mean is set up routines for pathfinding, heading for player, fleeing from player, attacking, hiding, searching for the player - so they can then be called by the AI routines.
I hope this helps. Bear in mind this is just my own approaches to AI and others may have different ideas on the subject.