I've done this many times before and never had an issue.  Charm a NPC and use them for whatever is necessary. Get tired of NPC, petrify them.  Go about merry way.  Well this time, I lost my pet too...
Quote:
Group: MYCHAR's Party
(F1)  [   Zieg, the sl]    (F2)  [   a thick-mane]    (F3)  [---------------]
(M1)  [---------------]    (M2)  [         MYCHAR]    (M3)  [---------------]
(B1)  [---------------]    (B2)  [---------------]    (B3)  [---------------]
Characters                 Rank    Pos  Here  Follow  Prone    HP    ME    PE  
MYCHAR                     Leader  M2   Yes   No      No     100%   80%  100%
A thick-maned lion         Member  F2   Yes   Yes     No     100%  100%  100%
Zieg, the slaver           Member  F1   Yes   Yes     No     100%  100%  100%
[HP:100%][ME: 80%][PE:100%]{7,Nature,1224:2pm}
>
c petri zieg
You start to concentrate.
[HP:100%][ME: 80%][PE:100%]{7,Nature,1224:2pm}
>
You utter the words, 'szculayuqann'.
Your petrification spell turns Zieg, the slaver to stone!
Zieg, the slaver is DEAD!!
One of your members has left the party.
[HP:100%][ME: 70%][PE:100%]{7,Nature,1224:2pm}
>
A thick-maned lion stops following you.
You scratch a thick-maned lion.
[HP:100%][ME: 70%][PE:100%]{7,Nature,1224:2pm}
>
You scratch a thick-maned lion.
A thick-maned lion slams into you and sends you sprawling!
Your armor protects you from the physical affects of a thick-maned lion's bash.
A thick-maned lion scratches at your chest, barely wounding you.
A thick-maned lion scratches at your stomach, barely wounding you.
Overall, a thick-maned lion has a few scratches.
It looks like for some reason, the code has me attacking the pet...