Method 1 is the built-to-purpose NPC: If your companion is a healbot, make it appropriate to the characters or adventure level, give it level appropriate training in medicine, combat essentials (athletics, acrobatics, or don't if you want them to be disabled by grapplers) and some special interests to shore up some weaknesses in the party. Maybe a specific lore or two for flavor. Find some appropriate feats to tack on like Ward Medic or Godless Healing if the healing isn't magical and operate like that. You get everything you reasonably 'need' with none of the extra bells and whistles from player sheets. Built exactly to purpose, approximate to a player, a level or two below just to make sure the players don't think to push the henchman forward in combat lest they lose them. Level adjustment will mean the henchman gets hit and crit more, and as soon as they realize that they should strategize around protecting him in combat. If you allow him to participate in combat that is. Consider morale rolls if the player treatment is particularly bad. Runes are optional for their weaponry but will help them stay relevant in combat math. You can use some of the weirder property runes to make them stand out and stoke some interest in your players to discover fun property rune types.
