[There's that pleased beam on her face. Most like to call it smug, but really she's just happy Katara is interested.]

It's just a really happy memory manifesting itself in a spell. A Patronus is meant to protect against something called a dementor in my world. It's a soulless being that sucks happiness from everything and everyone it touches. A Patronus will counter that with happy feelings and energy, but the caster has to be able to draw upon a very strong, happy memory.

[Terri the otter tilts her head a little further.] She's used to being around a coyote pup that likes to chase her. You can touch her if you'd like. [She'll feel kind of solid, but kind of cloud-like.]