All the hirelings are fully rolled characters with unique AI scripts and a handful of abilities exposed on the bar. I've used Cleric / FVS hirelings extensively because properly managed they are a great source of HP and stuff like remove curse / restoration / ect. Anything outside of that and they are pretty bad, like when I was playing my DD Radiance Cleric, I summoned another cleric and would use their SP to heal and their DV to restore my SP. Out of all of them Larafay is my absolute favorite, not because of Comet Fall or Destruction, but because she will run around spamming Greater Command on everything. Right Click disable her offensive spells and she pretty much casts nothing but Greater Command and heals. There are some others, usually at least one half decent cure bot every level or two, just don't expect anything greater then "cure" out of them. I really wished they would give us more versions of Larafay cause damn she's useful.

Note on Offensive / Defensive vs Follow / Stay, if you have them on Stay and Defensive, they almost entirely shut down. You could be at 10% HP remaining and standing next to them and they won't cure, then you toggle Offensive or let them move and they suddenly decide to heal. Also status removals work the same way, you have mummy rot and they just stand there, toggle to Offensive and they will cast remove curse + remove disease. So there is some skill to actively managing your spare pool of HP and it's something you only get with practice and working with each Cleric / FVS hireling.