[ To that, her words, he actually seems a little surprised, but the more he thinks about it, the more he gets it. ]

I'll make a contract with you, to ensure we both are bound by the rules we set in place. Portions of your Aura, in exchange for my services as a demon. You'd be able to use my magic, share some of my abilities, and since you said you need Aura to defend yourself, I'll protect you when you need.

[ It's mostly the last part that feels important. The other parts just sort of come part and parcel with demon contracts. ]