The 19-year-old defender came through the Jambos' youth system but joined the Easter Road club last month after being told by their administration-hit rivals from Gorgie that his services were no longer required.
Since then he has spoken about little else but he is keen to be associated solely with the green and white as quickly as possible.
Ahead of Friday night's friendly against Raith Rovers in Kirkcaldy, he said: "All the talk now is obviously about me coming from Hearts and it is always going to be there.
"I get asked about it all the time but hopefully there will come a time when people will just forget about it and just think about me as a Hibs player.
"Hopefully if I do well enough this season the fans will see past that and see that I am a Hibs player first and foremost and I am here to do a job for the club.
"I don't have anything against Hearts. But now I am at Hibs I am only concentrating on being here."
Last season came to a premature end for Mullen in March when, ironically, he suffered a fractured foot during the Edinburgh derby against Hearts.
He scored with a free-kick on his Hibs debut in a 3-1 friendly victory over the Gibraltar national team last week and is looking to be ready for when the season starts in earnest next week with a Europa League tie against either Drogheda or Malmo.
"First of all, I want to get match fit after last season and try to get as many games as I can," he said.
"I am back at training for two weeks and it is starting to come together now, I'm just lacking a bit of match sharpness.
"Europe is a great incentive, it will be a massive game and massive night so I am trying to push myself as hard as I can to get into the team for that."
The former Scotland Under-17 player admits he was concerned about his future in the several weeks between leaving Hearts and signing a one-year deal for Pat Fenlon.
"Obviously you worry when you are not in a job," he said. "With the financial situation in football, it is not easy, contracts don't just get handed out easily.
"So when you get released you are thinking 'will I get another team?' or 'where will my next team be?'
"I was worrying but when I looked at my offers, Hibs was the best I had and now I am here."