Johnston and Luke's understudy Cameron McInnes are off-contract at season's end with McInnes the more likely of the duo to re-sign despite attracting attention from St George Illawarra and Manly.

Luke stunned teammates when he confirmed Fairfax Media's report that he would leave the club at season's end to join the Warriors for three years. It was the prospect of facing his teammates that  haunted Luke most, despite having had conversations with club owner Russell Crowe and coach Michael Maguire. Luke said he was "shaking" when he told the Rabbitohs squad at Redfern Oval.

Luke decided he would return to New Zealand during the Kiwis Four-Nations success last year. Having spent extended time with his father George, Luke knew New Zealand would once again be home. His desire grew stronger during the Auckland Nines and he finally broke the news to Maguire last Tuesday, having asked the coach to meet him during a scheduled break for the players. Luke said Maguire tried to talk him out of ending his stint at South Sydney two years prematurely.

"Madge [Maguire] gave me the all clear, he wasn't too happy about it, but he's a passionate coach and passionate friend of mine," Luke said. "It's something I've been holding on to, this club is all about honesty, and if you've something on your mind, you say it. [Maguire] knows how passionate I am about being home. He could see it every time I went home. During the Nines I didn't want to leave.

"He's been really understanding and supportive."

Shortly after the meeting with Maguire, the initials "RC" popped up on Luke's phone.

"I had a little talk to Russ," Luke said. "He's a bit like Madge, very passionate, and me and Russell are pretty close. I'll get to spend some time with that fellow before I go.

"He asked me 'what's going on?' He said 'you can't beat family', and 'do what you have to do'."

Warriors boss Jim Doyle flew to Sydney on Thursday to sign Luke. It caps a rich recruitment drive by the Warriors, who secured Roosters fullback Roger Tuivasa-Sheck and have tried to entice St George Illawarra prop Mike Cooper.

Luke's teammates were shocked by his defection. Thomas Burgess said Luke's speech was greeted with a round of applause from the playing squad.

"I was surprised," Burgess said. "It was very moving. Everyone was happy for him. He just said he is doing it for his family. His heart is still with Souths. He said he'll always bleed red and green but he'll have to add a few more colours to that."

Luke said he wanted an opportunity to expose his young children to the New Zealand culture.

"My son," Luke said. "He was born here, speaks Australian and sings the national anthem. Now I'm taking him home.

"I think I've done enough here. I've been over here about 12 years, and I think it was time to go home.

"I've got my kids and I want to take them home to learn the culture and obviously learn the history of New Zealand.

"My brother has kids as well, and for them to grow up together, that played a part.

"I've been in my dad's ear. Dad didn't believe it because I'm pretty loyal to my team. He didn't really see me in the colours, but I gave him a call about a week ago and said, 'Dad, I think it's time to come home'. He said 'what are you going to do?' Then it happened."

Luke leaves at a time when understudies Nathan Peats and Api Koroisau moved on in recent seasons to push for more regular first grade spots. He has endorsed McInnes to take over as the club's long-term hooker.

"He's a bit like Luke Keary," Luke said. "He's a hothead. He has it in him, he's pretty quiet, so they're the ones you have to watch out for."

Back-rower Chris McQueen backed McInnes to make the adjustment to first choice dummy half.

"He is young and very hungry," McQueen said. "He just wants to rip in. He is a professional."