[quote=@Sparkwell]
<Snipped quote by MelonHead>

I agree with [@MelonHead]'s analysis. Orcs, even the regimented and outcast Orcs of Nar Mat Kordh-Ishi, are not going to appreciate being used in a manner that taints their reputation. Perhaps the siege is laughably easy, and the Orcs find the heir/claimant inside relatively defenseless, leaving them in a situation where they (as Orcs) have to address the fact that they've basically been hired as executioners to do the dirty work of killing the heir in order to avoid him/her being a problem later.

Getting an Orc mercenary group to do it gives the employer/faction who hired Nar Mat Kordh-Ishi plausible deniability that "they never meant to have him/her killed... it was those brutish orcs that kill everything in sight, blame them". Thus, the Orcs are being framed as unreliable and brutal and likely being set up to be disposed of later if they follow through on what the employer asked of them.

Something like that sound appealing?
[/quote]

Actually, you pretty much nailed the twist. These orcs don't act quite according to the script. Whoops.