I love Dylan Keogh, yes, grumpy, sarcastic but very funny and I was so pleased to see him back (well, I hope he's back). He might not always be popular with the patients and other staff but he's popular with the viewers. :)
He left two years ago because he found working with his estranged wife difficult... the awful Sam Nicholls, "Stand aside everybody, I'm an army medic don't you know!". She got together with Tom, the pediatrician and after Dylan finally agreed to the divorce and left she and Tom married and thankfully left too.