By Olivia Wheeler David Leon made a surprise return to ITV drama Vera on Sunday night, 10 years after he first left. The fan favourite is back as DS Joe Ashworth for series 13 of Vera after Kenny Doughty, who played DS Aiden Healy, stepped down following the Christmas special. Joe’s return spells trouble for Vera, as he reveals just why he is back and what has been going on in the last decade or so that has brought him full circle and back to his first boss. However, some viewers fear there could be a ‘sinister’ twist coming up as they complained Joe appeared to be behaving differently amid hi…