For as long as he has been one of the biggest superstars of the WWE, fans have begged the company to turn John Cena heel. He hasn't really done any heelish behaviour since he was using his Doctor of Thuganomics gimmick.
Since he debuted on the main roster in 2002, Cena has become a global superstar, winning 25 championships including 16 world titles, as well as headling WrestleMania on five different occasions. He is slowly starting to make his mark outside of the WWE in Hollywood as well.
Yet, throughout that 16-year period he has been on the main roster, WWE fans have begged the company to turn The Leader of the Cenation heel and push him in that direction, but it has never happened. However, that's not to say the company has never thought about it.
According to Mike Johnson of PWInsider, via Ringside News, WWE thought about turning Cena heel in 2012, and that a lot of wheels were put in motion to make that happen. New outfits and ring gear were even made to go along with the heel turn.
However, Johnson states that WWE ultimately pulled the plug on the idea due to merchandising, as he said: “I don’t know who he was going to feud with. I don’t know if creative was ever “locked in” but I do know Cena had come up with new ring entrance.
"He came up with new outfits he was going to wear. Things like that. It was probably around 2011 or 2012. So it was about four of five years ago from now. So yeah, it was right around the time he had the K-Mart kids campaign. So, if you google that and find out when that campaign was, it was pretty much around that time.”
2011 and 2012 was the time where The Rock had returned to the WWE and CM Punk was one of the biggest stars in the company, two superstars which Cena feuded with during that period. He easily could've been a heel in both of those feuds, so it's believable that a heel turn could have been in the works.
With Roman Reigns now being the new top babyface of the company due to Cena's now part-time status with the WWE, it will be interesting to see if WWE would revisit the idea of turning The Leader of the Cenation heel, as now would be the perfect opportunity for them to do so.