"Unable to use first person pronouns" is one of the hotter speech restrictions. The expression of self is such a key part of the performance of identity. Though it's elevated quite a bit further by mandating a replacement, especially a demeaning one. Ideally you want something that signifies a power dynamic (eg 'your toy', 'this humble servant') or is especially ego dystonic (can't really provide examples without the context of an individual. take one of their deep personal beliefs and invert it). The goal is to force the subject to perform an identity unlike its own, and in doing so be adorably uncomfortable in its new position. Though, some subjects will simply avoid any usage of the first person at all and thus not be tripped up by any restrictions along those lines. Or, as this little alice does, it might simply enjoy the game of it.
Adding speech restrictions to my kink list…
