Inquisitor - how to use this class?

[One]

I wouldn't take inquisitor in my party as I don't quite understand the role of this class in game (it's something close to paladin - isn't it?)

But Jaethal is Inquisitor and I really love her personality (she is such a bad girl, you know), so I am trying to understand how to make her fit into my party.

The only idea I have is to cross-class her with Sorcerer (Empyreal Sorcerer the one which is based on Wisdom - she has a strong Wisdom) - is it a bad idea?

Maybe it's better to cross-class here with a Ranger?

Or is Inquisitor class good enough itself? For what role is it good then?

[Greybishop]

Think of it like a holy sorcerer ranger. They only get up to 6th level spells. Medium armor, can be a beast in combat and at range with their judgements. While the one in game is given a scythe, she can easily be set up with a bow and do ranged damage as well. They can buff and debuff, her build is primarily debuffing.

You could easily dual class ranger and you wouldn't lose for it, you could even focus in ranger with two handed fighting for the scythe or bow fighting if you want to go either way.

[Nay]

Inqusitor is a great class that can perform almost any role without multiclassing, so just going straight Inquisitor all the way is fine.

The thing with spellcasting classes is that they tend to lose more than they gain when multiclassing, unless their multiclass also progresses their spellcasting. For example, if you multiclass with Empyreal Sorcerer you end up with both your Inquisitor and your Sorcerer spells being weakened. You can partially fix this by taking the Mystic Theurge prestige class which progresses both Divine (from the Inquisitor) and Arcane (from the Sorcerer), but something like that is more for versatility than for power.

As for Jaethal, she seems to be intended to be a melee fighter who uses spells to support herself and the party. Scythe is unfortunately not a great weapon, so you can either give her a different weapon (Fauchard would be perfect for her IMO) and effectively waste a feat, or you can stick with the much more flavorful Scythe and don't worry about choosing the "perfect" weapon for her. Pick spells which she can use to buff herself and the party, as well as Inflict Wound spells which she needs in order to heal herself (since she's undead, Cure spells and Wound spells are effectively reversed for her). Alternatively you can focus on her spellcasting, in which case you probably want to pick more offensive spells and summons. For both approaches you can just stick with Inquisitor all the way.

[Darkfireslide]

Inquisitor is a divine version of a Magus. Like the Magus they are exceptional damage dealers in melee and at range and their Judgments provide massive offensive bonuses to the party.
Jaethal works as a flanker (Don't let her be the first one to charge in, she will take way too much damage and die very easily), charging archers and spellcasters to dispatch them, but she also works as an archer because Judgments work with melee and ranged (You need the feats Point Blank Shot and Precise Shot to make this work). Her spells are good support and offensive support as well. Like all physical damage dealers, try to get every buff possible when using them: Linzi's inspire courage, Bull's Strength spell, Divine Favor spell, Bless spell, etc. Her critical hits are frightening.