Nothing so sinister. If this were permanent and you were a cat or small bird, I'd set you to perform errands maybe. Fetch me this item, or scout this area. That sort of thing. For something more like yourself, there could be a bit of that, but primarily I'd have you fight for me.

[She stirs a finger in the air, tracing the wind.] It's not as if I can compel you to do any of it, however. Independence is an important trait in familiars, and the less simple they are, the more independence they have.

[It's important to have familiars capable of reasoning, who can learn and react without input if need be. And for something like a Servant, even at the risk of betrayal it's absolutely necessary, being the only ones strong enough to fight other Servants.]