My cat suddenly started to aggressively demand attention?

Many cats when they get older (8-13 years) tend to go through a stage when they are much friendlier and demand more attention. No one knows why this happens,some say it`s because they know they`re getting old,but no one knows for sure. It`s certainly possible that your cat is lonely because the other ped away,and is trying to fill the void with your attention. There isn`t anything you can do about it other than give your cat the attention it wants.