Powers: Those things Dogs do
Todd isn't exactly an evil ex-boyfriend as much as he is an evil ex-pet. Ramona first picked up Todd soon after she broke up with Todd. In order to get over him in her own way she named the dog after him. She learned not too long after that this was probably the worst name she could have given him seeing as how he wasn't actually a he, but a she.
She decided not to change the name despite Todd being a she, and looked after Todd for a few years until she finally moved again. Heartbroken, Todd began searching for her master only to discover that she had a new pet. Gideon the cat.
While she doesn't really mind Scott very much, and actually enjoys playing with him, whenever he steps on her tail she goes into a fit of rage and chases him for hours. Her hate for Gideon on the other hand exceeds that of cat vs. dog. Whenever she sees Gideon she gets so angry that she begins emitting flames which burn her fur, turning it black.
So Scott, looks like you got a lucky break this time. Gideon however, really needs to watch his tail.