Mechanical ways to build a character with a hungry monster within? (slight Monstress spoilers)

[gyrfalcon]

I've been reading and loving Margerie Liu's Monstress and it's got me thinking about a character with a hungry monster inside her.

Some options I've considered:
- Warder (Fiendbound Marauder) is 3rd party (Dreamscarred Press) but seems like a great way to capture someone who partially transforms into a dangerous monster.
- Spiritualist (Exciter) or Bloodrager seem like reasonable Paizo options for modeling someone with a beast within her as well.
- Inquisitor (Sin Eater) seems like a reasonable way to mechanically benefit from devouring one's foes.
- Vigilante gives the ability to have dual alignments.

What I'm looking for: is there anything (class feature? drawback? something else?) that simulates a need or desire to kill? I like the idea of a tension between a monster inside that just wants to eat vs character who's morally opposed to that monstrous urge. It's possible to just RP it without any mechanics...but are there other mechanics you think might fit it?

At this point, I'm playing with an idea rather than making a character for a specific game (so don't have any specific build/level/Paizo-only requirement).

Given all that, what options would you consider? (Let me know if this needs clarification as well.)

Thanks!

[Tarik Blackhands]

An Alchemist into Master Chymist is another option as is a Dark Half Psychic (if you want physical changes to go with that, I recall a turns-into-Chthulhu-lite Mutation Mind build as well).

I honestly don't know of any specific traits or similar that will give you a compulsion but most of the things you listed (and my additions to an extent) all operate off (or can be refluffed fairly easily) to have a not-so-nice critter inside that does bad stuff when its out (like eat people alive).

[K-kun the Insane]

I personally love the Posessed trait for the idea that something else answers with knowledge that the PC has no way of knowing. It's not much and it's not great, but it's something.

[Hubaris]

Spirit Ridden lets you channel a spirit to gain skill bonuses which leads into Channel Spirit which allows you to gain bonuses based on it, while it gains partial control over you. This can be further boosted with Spirit Focus. Check out the Medium as a whole, specifically the Spirit named The Butcher which has a need to kill.

Additionally if you want more of a spirit vibe instead of a monstrous physical urge, there is the Possessed Hand tree, which allows you to have a Hand that can actually perform its own actions (somewhat) with Hand's Autonomy; and can eventually become a familiar with Hand's Detachment. You can even let it look for you with Hand's Sight and know for you with Hand's Knowledge.

There are also the Damnation Feats which sell a part of you off and make you more Evil, possibly giving you more of an urge to kill and are tempting as a whole. You can simulate growth this way.

Another option is the Variant Multiclass Rules for the VMC Oracle which allows you to take the Hungering Curse; forcing you to have to bite something once every battle to remove your sickened condition.

There are plenty of Archetypes as well, from the Raging Cannibal Barbarian to the questionable Brute Vigilante. There is also the Master Chymist Prestige Class which is glorious for this as well, very Mr. Hyde.

Finally you can always ask your DM to look at the Corruption Rules which simulate your character having a massive drawback, and some bonuses due to it. For example your character has a desire to feed on blood or else.

Perhaps this will spark some ideas.

[gyrfalcon]

Thanks for the suggestions, these are a ton of great ideas!

Hubaris, thanks for suggesting I check out the Medium. That led me to the Fiend Keeper and Outer Channeler archetypes, both of which totally fit the flavor I'm going for.

[cavernshark]

To add to Hubaris' list, the Fiend Keeper archetype for the medium might also serve well. It's a Grippli archetype, but could easily be for any race and might fit what you're trying to do.

[Melkiador]

I'd be more worried about playing someone opposed to killing in what's likely to be a party full of murder hobos.

[JDLPF]

Get a tumor familiar with a chaotic evil alignment. Then you can literally have a character with a hungry monster inside him!