A snake in the grass

Grass snake

The other day I was walking my dog in the woods near where we live when she nearly trod on a snake about as long as my arm (honest! See picture). Bianca - bless her heart - isn't the brightest thing on four legs and doesn't always notice everything that's going on around her, so she didn't see the snake as it shot off into the bushes, but I nearly jumped out of my skin. 

Bianca

Anyway, this set me thinking and I've decided I need someone to add a surprise element to the story, so a new character is going to appear in Chapter 29. I may have to cheat a little bit and back-fit references into earlier chapters to make the character more plausible, but it's my book so I can do what I want.
The question is, should this character be male or female? Hmm!