I think Irem would blast Adrian than the bimbo who was forced to cast it
. Anyways Adrian is not going to waste such valuable spell as hold person to get quickie anals with other prisoners (when he has virgin and untrained elf bimbo which is needing for good hammering to keep her in line anyway). As when said spell can be used against people who actually try attack Adrian or are dangerous.
He would ask stuff in return for renting Tiffany's services; it can be sexual or directly beneficial depending on individual and their skills. So Irem as alchemist may promise brew healing potions once she gets ingredients or other useful alchemy. Or she can save ingredients for herself if she follows same path as other woman is doing with Adrian. Those who bring his stuff without aid of Tiffany (or contributes otherwise well for the group like hunting food), get rewarded (either play time with Tiffany or other reward).
Of course they can question Adrian's claim and try take off the bimbo from her, but it's one reason why I ask he has his armor on so he would have in start equipment advantage over other prisoners. Hope then that once others find pieces of their gear they have learned to appreciate Adrian's efficient leadership skills.
Also another can be that once he finds tattoo set and goes hunt magic ingredients himself he brands Tiffany to be his bitch officially with Sin rune, so that she cannot obey anyone else and defying orders from Adrian will burn her and may kill her slowly (but more likely her will breaks and she submits with nasty manacle burns in her body as sign of Asmodeus displeasure).