To use an old cliche (Which I hate to do) they are walking examples of "Marmite Housemates".

They are so polarizing and carry essentially the same personality traits and the reason why they both have support could be that people who hate Perez could be championing Katie for taking him on. And people who hate Katie might be championing Perez for taking her on.

The thing is when one of them goes...the other just becomes the ultimate evil with nobody in the house who could battle them for that crown. There will be nobody acting up enough for people to go "Ah well at least their not as bad as them" because Perez and Katie are so cut and dry in whether people like or hate them.

Very rare shades of grey with the two.

I think IF one goes...The other would probably follow very shortly