Both of these need to be at least rank 3, and you’ll probably want to end up maxing one. Get him up to 3rd-level as a Cleric and split his Skill Points between Knowledge (Arcana) and Lore (Religion). Harrim starts out with one level as a generic Cleric.

Compared to a single-class caster, you’ll be behind by perhaps one or two spellcasting levels, which is a huge deal - perhaps crippling for a primary spellcaster - but the end result may well be worth the downsides. The downsides, of course, are that you’ll need to waste several levels on Cleric/Sorcerer, during which you obviously will only be progressing in one of your two spellcasting classes. The solution is simple and dare we say, obvious a Sorcerer (Empyreal Sorcerer) will use the character’s Wisdom to determine spell potency, and when you qualify for Mystic Theurge at 8th-level you can begin progressing as both a Cleric and Sorcerer simultaneously. Of course, Cleric spells aren’t the best, and if you just needed a dedicated healer, why not use Tristian? In fact, there’s not much of a compelling reason to keep most any Cleric as a single-classed character. He can be a downright fearsome blaster-caster if we make the attempt. He’s got an 18 Wisdom and access to the Destruction Domain, which will net him spells like Disintegrate, Horrid Wilting and Tsunami. Instead of trying to cobble together a complicated build and tossing good equipment at Harrim to make him a mediocre off-tank (something that’s possible, yet of dubious utility) we decide to abandon the things Harrim’s not good at, give up any pretenses of being a front-liner, and focus on what he can do well.

Pathfinder kingmaker companions