For many years the two sports were sworn enemies and were forever sniping at each other and pinching players - mostly going the way of league as it paid the dosh.
Once rugby became professional in the mid-1990s, the dislike of each other softened and the two codes learned to live with each other.
It has become more about what they can do for each other and to help each other out.
Now that friendship has been extended to the Kiwis Four Nations tour where Highlanders doctor Greg Macleod has been brought into the touring party.
New Zealand Rugby League chief executive Alex Hayton and New Zealand Rugby chief executive Steve Tew were both at a function a few months ago and started talking about sharing intelligence and resources.
Hayton mentioned the Kiwis no longer had a doctor for the end-of-year tour and if it was possible for NZR to provide someone.
Macleod put his name forward, wanting to aid his personal development, and now finds himself on the way to England with the league side for the Four Nations tournament.
Macleod has been the doctor for the Highlanders for the past two seasons and has also worked with the Otago side.
Born in South Africa, he came to New Zealand as a teenager and then embarked on study at the University of Otago when he left school.
He completed degrees in physical education, science, physiotherapy, and medicine and surgery and postgraduate diplomas in sports medicine and child health over the following 10-plus years.
He has also worked as a house surgeon at Dunedin Hospital for two years.
Former Highlanders physiotherapist Karl Macdonald will be working alongside Macleod on the tour.
Macdonald worked with the Highlanders from 2008 to 2010, working with former coach Glenn Moore. He is based in Invercargill and has worked with the Southland rugby team for many years.
Macdonald has a league-playing background and also played premier rugby in Dunedin for Zingari-Richmond. Macdonald was Kiwis physiotherapist in 2007-08, including for the World Cup triumph in 2008.
He became involved with the Kiwis again in 2014 and will be with the side until the World Cup next year.