England have never recorded a one-day international whitewash in the Caribbean, 36 years on since their first attempt.
But one more victory in Barbados on Thursday, after back-to-back successes over their inexperienced hosts in Antigua, will set that record straight.
Roy, likely to be in company for the first time on this tour with his fit-again opening partner Alex Hales, is one of England's biggest weapons.
Fielding coach Paul Collingwood, who previously led England to their only global trophy to date in the West Indies at the ICC World Twenty20 seven years ago, spoke in a broadcast interview this week of his awe at the power in the current line-up – and specifically of Roy's "brute strength".
The opener demonstrated all of that with seven fours and a six in his 48-ball 52 as England sealed the series with a four-wicket win at the Sir Vivian Richards Stadium.
Roy was annoyed at himself for failing to go on to a century, and leaving Joe Root and Chris Woakes with lots of work to do after a middle-order collapse followed his own dismissal – caught on the long-on boundary off Ashley Nurse.
He insists nonetheless he will carry on attacking.
"It was just execution [that was wrong]," he said.
"That's all it was – 10 rows back, and it's a different story. But that's the way I play my cricket, I push myself and I push the boundaries."
England want him to do just that, en route to this summer's Champions Trophy.
For Roy, though, the aim is not just to keep hitting the big shots but to make sure he can do it for longer – having registered six ODI half-centuries without going on to a hundred since his career-best 162 against Sri Lanka at The Oval last summer.
"That's not the way I want to be known as a cricketer," added the 26-year-old.
"I want to be known as a guy who is going to win matches and score big hundreds, be that solid guy at the top of the order.
"Yes, make quick 50s and 60s every now and then - but big hundreds are at the forefront of my mind. I'm extremely driven (to do that).
"Last summer was frustrating again, getting 50s and getting out.
"Fifties, 60s and 70s don't necessarily always win you games. Big hundreds win you games, and that's what I want to be - so tomorrow's a huge opportunity for me again to hope to convert a 50."
He will do so after returning to training between the Bridgetown downpours on Wednesday afternoon, and unexpectedly finding himself answering questions about England's day off on the beach the previous day.
Roy was taken to task after photo-splashes surfaced in online and print media of England players and their girlfriends enjoying the sunshine and Barbados coastline – including one press-conference suggestion that they were therefore not respecting their opponents.
Roy took issue.
"We're not allowed to have a day off?" he asked.
"Today we have training. Yesterday we travelled, the boys were stiff, so we had a day off."
He also insisted England do not believe they can take it easy at the end of this short tour.
"That's not at all what we're thinking - we're extremely excited to make it 3-0 ... big game tomorrow, that's our aim," he said.
"We've won the series, but we don't want to stop there.
"We don't aim for mediocrity. We want the best."
Hales' return in place of Sam Billings, following his recovery from a broken hand, is likely to be England's only change to their winning team.
West Indies v England teams
England (possible): EJG Morgan (Captain), JJ Roy, AD Hales, JE Root, BA Stokes, JC Buttler (wkt), MM Ali, CR Woakes, AU Rashid, LE Plunkett, ST Finn
West Indies (possible): J Holder (Captain), K Brathwaite, E Lewis, K Powell, S Hope (wkt), J Mohammed, J Carter, C Brathwaite, A Nurse, D Bishoo, A Joseph
Umpires: G Brathwaite (WI) and R Palliyaguruge (SL)
Third umpire: C Gaffaney (NZ)Match refereee: J Crowe (NZ)
Fast Results
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