Based on what we know of Erin by the end of the series, I uh... doubt she was the one who came up with Jamie's codename. (I think that's not too spoiler-y for you newbies out there!)

But I doubt Hazel came up with it, either, and I can't picture her suggesting the codename "Sea Otter" for herself.

So, I think we can all agree: McPedro came up with all of them.

Here's the original post! And here's the chaser post!