Thanks @Incredulous_Hulk that is quite interesting. Thanks for the info. I do hope that we get a weapon and vehicle api in the future - I can think of lots of fun things to try with that.
For everyone else: if you want to run code (ie execute OnDamaged(...)) you first need to subscribe to the damaged event for the FortCharacter you are interested in. Something like:
FortCharacter.DamagedEvent().Subscribe(OnDamaged)