I have basically two versions of this, what I call the PC version and the NPC version. The NPC version is easy, evil and creepy, doesn't need a lot beyond that because players are frankly incredibly unlikely to ever learn much about their background or motivations.
The other is the PC version, which is much less overtly evil (and hence much more likely to get to see extended amounts of play).
We're going to be talking about the PC version (obviously).
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Basic concept origins:
Mostly a combination of two other characters from various sources as the starting point. Erandis d'Vol from Eberron (whom I made into a young teenage girl when she was forced into becoming a lich, and generally made a more sympathetic character), and a half-orc character I had once who's motto was basically "People see what they want to see, and as long as that is what you show them, they don't bother looking any deeper". Basically the smart guy who played dumb brute.
Combine those with a smattering of "ancient evil that looks little and innocent", like Babette from Skyrim or Claudia from Interview With A Vampire (with some smatterings of Samara from The Ring) and you've got the basic idea, the innocent looking little girl that is really a monster. Because creepy little kids are creepy.
Oh yeah, and the villain Baby Doll from Batman, as she's basically the non-magical epitome of the concept, IMO.
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Mechanically:
Actual crunch-wise, its an adult Halfling Jinx Gravewalker Witch with Childlike, and possibly a 1 level dip into Juju Oracle for the hitdice boost to Animate Dead.
Lots of ranks in Bluff to present themselves as a human child to try and squirm their way out of situations where being a necromancer would usually get them run out of town (at best). The whole "boo hoo, I'm lost and these scary monsters were going to eat me!" routine.
Most of the feats and the like are pretty standard and self-explanatory, make lots of powerful undead minions.
Likely going to take a lot of debuffing hexes along with Cackle (reflavored to be creepy childish giggling) to be sort of an anti-bard that debuffs enemies to make them easier prey for the undead minions.
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Background/Fluff So Far:
The short version is they are an ex halfling slave from Cheliax that managed to escape due to looking a great deal like a human child, who while living on the street trying to get out of town finds an evil possessed teddy bear that promises to give them the power to escape to freedom (aka its their poppet). They agree, and manage to get out of town. Now there's a childlike looking Halfling with a demonic stuffed animal whispering in their ear who tends to see the dead as tools and resources rather than, well, a corpse.
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What I'm looking for help on:
For the PC version, I'm clearly going to have to bend the character less Evil and more Neutral, so general tips on how to keep it more "You wear dead animals and enslave live ones to do your work, I just use a little bit more" are appreciated. Things like only using animal or monster corpses instead of humanoids to avoid the whole "Thats my grandmother's corpse carrying your pack!" moments, how to hide/conceal your undead to keep from making a scene, that kind of thing.
Tricks/mannerisms to help sell the manipulative fake-child aspect.
Any potential mechanical tricks/combinations that would go well with the concept.
Oh, and it is a given that the PC version would not be hiding what they really are from the other PCs/players beyond the very beginning, it would be limited to manipulating the NPCs.
My character had a cohort who used Appearance of Life on skeleton servants to conceal them, when needed.
My character had a cohort who used Appearance of Life on skeleton servants to conceal them, when needed.
Oh thats a good one. Zombie minions that look like mommy and daddy.
Quick note: The Childlike feat only gets a small boost to disguise, and Disguise is not a class skill for witches. If you can find a trait that gets you the Disguise skill as a class skill, definitely take it. If this is a home game, see if you can convince your GM to let you take Almost Human (normally a half-orc race trait) which gets you Disguise as a class skill and +4 to Disguise to pass as a human.
Note that Bluff is also not on the clsss skill list.
Only partly related, but I once played a gnome whose childhood penchant for dried flowers grew to include dried animals...and eventually reanimated dried animals. He rode a zombie tiger that he decorated with garlands of dried roses and strawflowers.
Backstory in the linked profile, if you're interested.