Departing St George Illawarra forward Trent Merrin has been painted as "greedy" and "selfish" but admits he would have stayed at the club had they not reneged on a handshake agreement reached last year.

The 25-year-old has vowed to give his all in his final season at the club, but admits he was disappointed Dragons officials didn't make good on verbal assurances surrounding a contract for 2016 and beyond. "At the start everything was promises and handshakes, which I was happy with and was happy to stay," Merrin told Fairfax Media on Wednesday.

"But as the process went on, it unfolded in the wrong direction and things weren't as promised. At the end of the day I know the club isn't in the best [salary cap] position at the moment. That's no one's fault, it's just the position it has been left in. That's why there's no sourness or bitterness towards the club. I owe the club everything. That's the way I'll play this year and the way they'll be remembered in my heart."

Merrin was criticised before Christmas after knocking back an offer that was different from the orginal handshake agreement. At the time it was described as "the best offer the Dragons have ever made a forward".

The attack on his character that followed was difficult for him to deal with, however Merrin insists the decision to leave and sign a three-year deal with the Panthers wasn't motivated by money.

"I'm not going to sit here and lie and say it felt good being painted out to be the bad guy at the start, as it would when you hear someone is leaving the club," Merrin said. "That's why I'm doing this to tell everyone that it's not the way it was. Obviously it does hurt being called greedy and selfish and everything I was accused of being. The fans deserve to hear what I have to say. My final decision on my future was not based on money. Obviously money helps, I'm not going to lie about that, especially in the business we're in.

"We get bashed for a living, so money does help, but my final decision was based on my playing future and where I feel I can play my best footy. I based it on taking my game to the next level."

The Sharks and Warriors were also in the hunt for Merrin's signature, however the final decision was between the Panthers and Broncos after a late push from former coach Wayne Bennett to lure the Origin forward to Queensland.

"I did have chats with Wayne and bounce back and forth with him because I hold Wayne in such high regard," Merrin said. "I definitely did think about going to Brisbane, but I weighed up every option and I've made the best decision for my future. I love Wayne, he's given me the best feeling you can get in rugby league being part of a grand final-winning team and winning culture. That's the best feeling you can have to have that culture around you and that family feel. The way he gets a team going is incredible, that's why it was definitely on the cards. But when I told him I was going to sign with Penrith he just asked if I was happy. I said 'yes' and he said 'well you made the right decision then'."

Merrin was named on the bench for St George Illawarra's season-opener against the Melbourne Storm on Monday night, sparking speculation over his immediate future at the club. However Merrin hasn't been deterred by his selection on the bench and remains committed to finishing his time with the Dragons on a high, vowing not to kick stones.

"I honestly hope and think I'm on the bench because it's the style of play we want to head towards," Merrin said. "People might say there's some bitterness there, but I'm not buying into that. I play rugby league - that's my job and that's what I have to do. If it means coming off the bench, I'm going to be the best bench player there is in the game. I owe that to the club and I owe that to myself. I've put too much time and effort into myself to go out on the field and be a sook and carry on and blame people. That's not the person I am. I've been kicked in the face as a kid growing up my whole childhood, but I haven't wasted all that time to get myself into this position to throw it away. This is life. I know fans and people are going to be put off by it but there will be a time in people's lives where they have to make a decision for themselves, and that's what I've done."