Im not sure about the adds but for bosses if the dps' were doing enough damage (Might or Percision) the strongest one will get aggro before the healer. However if none of the dps are doing enough damage then healer will most likely get aggro regardless. Its also like that for raids and bounties. If the tank dies or drops aggro, the best dps will be targeted for example in FGSE Zeus will lunge the dps that's dealing the most damage before any of the healers if the tank isn't broken out right away. In Patchwork if no one is doing enough individual damage to a bounty then the healer will get aggro if there is no tank in phase. This is before the change of course. If it even had anything to do with that.