Both opening batsmen from Barbados, Brathwaite and Haynes have worked together previously on technical components of Brathwaite's game but, more recently, the focus has shifted to the mental side as West Indies prepare to face England in their three-Test series behind closed doors, beginning at the Ageas Bowl on July 8.
"I had some words with Desmond Haynes back in Barbados," Brathwaite said on Wednesday via video link from the team's Manchester training base. "Me and him always had a good relationship because he was team manager for the Barbados team when I first started, so I had some chats with him. He was obviously an opener as well and that's been very beneficial to me.
"A lot of it is keeping it simple, you don't really want to complicate it too much. It's just simple advice, just about what he did back in the day. Three hours left in a day is always a tough period for an opener, or an hour. So it's just mental stuff that he helped me with... he was very strong mentally."
Brathwaite scored 134 and 95 when West Indies chased down 322 to win the second Test at Headingley in 2017 - their first Test victory in England for 17 years - and team-mate Shai Hope became the first man to score two centuries in a first-class match at the ground with 147 and 118 not out.
Since then, Brathwaite has suffered a dip in form, averaging 25.33 in his last 20 Tests. He made it into the 40s twice as West Indies defeated England 2-1 in the Caribbean 18 months ago but his failure to convert those starts, followed by even leaner returns against India and, most recently, Afghanistan has put him under increasing pressure.
Brathwaite did strike some good form with the bat during the West Indies Championship, reaching three half-centuries and scoring 40 or more on three further occasions for Barbados before the competition was halted with two rounds to go in mid-March because of the Covid-19 pandemic.
The absence of batsmen Darren Bravo and Shimron Hetmyer, who opted not to travel to England during the outbreak, only adds to the expectation on Brathwaite and Hope for this series, although Brathwaite doesn't necessarily see it that way. Nor does he give too much currency to his feats in Leeds last time West Indies toured England.
"That was almost three years ago," Brathwaite said. "Looking back at stuff I did I can obviously see things I did well, but that's history. I have a current job to do here and I'm ready, I'm raring to go.
"I'm up for the challenge... I know all the guys here can do well. I'm starting the innings and I'm just going to do my job, it's as simple as that. I know we have a good batting line-up and everyone's ready and raring to go, so no added pressure really."
Having said that, Brathwaite also believes that run-chase at Headingley could hold the key to success this time around for a side that, by head coach Phil Simmons' admission, has come to rely too heavily on its bowling attack.
"We've got to score runs," Brathwaite said. "Once you can put runs on the board we put our team in a great position. We've still got to be disciplined with the ball but I think potentially, when we won the game at Headingley, we scored runs, we chased down over 300 runs, so we've just got to put runs on the board."
"You've just got to be mentally strong. The last couple of series, we've got to be honest with ourselves, we didn't do as good as we know we can so we've got to buckle down and stay disciplined. Discipline will carry you a long way, in Test cricket in the whole and then especially here in England where the ball will potentially be moving. Once you can be disciplined throughout the whole day and not just for half an hour, an hour, I think that will bring forth big runs."
Brathwaite's discipline and patience stood out against England in the Caribbean 18 months ago, where he performed well against the seamers and the new ball, but fell to Moeen Ali three times in six innings. But he has never faced fellow Barbadian Jofra Archer, who is set to play West Indies for the first time in a Test since qualifying to represent England last year.
"Jofra is quality," Brathwaite said. "I've never played against Jofra, not even back in Barbados, but I look forward to the challenge. We know it won't be easy so you've just got to work hard. Our net sessions are quite competitive, our guys are quite aggressive so we're getting in shape."
Valkerie Baynes is a general editor at ESPNcricinfo