Right, so I've been using Mayu's Animation Overhaul all this time. It's great and is almost perfect, no, make that perfect for vanilla characters, but it doesn't cover characters created by mods, one of which is Knights of The Nine.

I find it annoying to see the Prophet standing there with the idle animation I used specifically for my character, a female (note that the dang guy is an old guy). Also, imagine the horror when I heard characters from Mehrunes Razor use the same animation AND voice used by my character in battle (hint: normal males don't use female voice). Now, the last thing I need is some burly knights screaming with Japanese anime voice.

Is there any way to make custom animations exclusive for PC? Maybe put them in a separate folder? I don't mind doing some work by myself, as long as the result is good. I only need someone to guide me the right way.

I see MAO works by redirecting skeletons for vanilla characters to a separate folder. If someone can tell me how can I do it myself (redirect custom characters to use the separate folder) I'll happily do so.

Also, for some reason Shivering Isles characters are not affected by the custom animations I use, maybe there's a trick in this?

Possibly stupid question, but are you using the tweak option to apply MAO skeletons to all NPCs when creating your bashed patch?
Also, there's an updated MAO for OOO atleast here: http://www.tesnexus.com/downloads/file.php?id=27636

I do not use Wrye Bash, I haven't learned how to use it. Don't ask why, but if it CAN solve my problem, I'll happily learn how to use it.

And no, I don't use FCOM or any major part of it

Ah, well yes there is an option in Wrye Bash that solves your issue. When building your bashed patch, you can choose to apply the MAO changes to all NPCs (vanilla AND modded) under Tweak Actors.

I see, thanks for the heads up. Guess it's time to try