How can I acquire Charm Person/Charm Monster as an SLA for my NPC?

Question

So, I'm creating the overarching villain for a campaign I intend to run - an Osyluth with class levels known as Molkor the Quartermaster - and I want to get him into the Fiend of Corruption prestige class (Fiend Folio). The trouble is that one of the pre-reqs for entry is Charm Person and/or Charm Monster as a spell-like ability, which Osyluths natively lack. Now, I'm aware that a single level in Warlock will solve this problem for me.

However, are there any other ways I can give this fiend Charm Person and/or Charm Monster as an SLA?

Answer 1

Well, Complete Mage has Fey Presence:

Fey Presence

[Heritage]

You share your ancestors' knack for playing tricks on the minds of others.

Prerequisite

Fey Heritage, character level 6th, Nonlawful alignment

Benefit

You gain the following spell-like abilities, each usable once per day: charm monster, deep slumber, and disguise self. Your caster level equals your character level.

Obvious problems include weird fey influence on your devil, and alignment issues. Both things I’m inclined to hand-wave (for players as well as NPCs), but they are there. Also requires Fey Heritage, which is basically garbage (+3 Will vs. Enchantments). I’ll keep looking.

Aberrant Dragonmark (Player’s Guide to Eberron) works for certain (Humanoid) races but not for an Osyluth (or much of anything else that qualifies for Fiend of Corruption, though I suppose a Half-fiend Human/Dwarf/Elf/Halfling/Orc could do it).

I’m pretty sure that’s it for feats.

For templates, Half-fey (Fiend Folio, same as Fiend of Corruption in the first place) is CR +1, gives charm person at will, and a bunch of other stuff that’s pretty useful (like flight). Of course, if you’re going for something that’ll increase CR, Beguiler (Player’s Handbook II), Dragonfire Adept (Dragon Magic), Sorcerer, Warlock (Complete Arcane), and Wizard all work, and I think Binder (Tome of Magic) does too.

Answer 2

Since you're the DM, you could just decree he has it and maybe fill out his backstory a little because of it - after all, it's not like he existed in a vacuum until the PC's stumble across him.

Maybe as a little fiendling he was trained in the seductive arts by a coven of his overlord's captive succubi, or maybe he was granted an enchanted silver tongue by a highly ranked devil in recognition of the time he talked his way into an angelic fortress (in fact I believe the Fiend Folio already has rules for fiendish grafts).

Player characters can acquire all sorts of weird abilities as a result of their adventures, so why not your over-villain as well?

Answer 3

I think that I would have introduced an artifact which grants the Charm Monster SLA in return for something (a couple of ability points?), maybe attribute it to the correct deity, and give the PCs access to it later in the campaign. That would give them an "ah ha!" moment.