They'll remember, too, that three years earlier he said publicly he wanted to leave amid rumoured interest from City. Supporters don't quickly forget, but they're usually willing to forgive, some more easily than others.
It's difficult to gauge how United fans feel about Rooney because there are so many different sections of the fanbase.
There are the thousands, millions the club say, of armchair or internet fans, who won't hear a bad word said about any of the players regardless of their indiscretions.
It's can sometimes look like the kid in the school playground who goes nuts when another kid slags off his dad.
At the other end of the scale, there's the group of 3,000 or so who watch United home and away. They follow the team week in and week out and represent a sample section of the more knowledgable supporters.
The away support at Swansea got the first opportunity to show how the United fans felt after a summer of claim and counter-claim.
Warming up on the touchline, Rooney looked sheepish when he ran over to the away end. But there were no boos, just a gradual chorus of 'Rooney' that got louder and louder. It wasn't a full show of support, but it was evidence that they are willing to move on.
As long as Rooney stays at the club, there will always be a way back.
He'll never feel the full force of the Old Trafford crowd unless he returns in another team's shirt. It'll be no holds barred if that happens.
But while he remains a United player, he'll get the support of the fans. The odd winning goal will speed the process along, but he'll never walk out of the home dressing room at Old Trafford with boos ringing in his ears.
For most fans, the Rooney saga has left a bad taste.
It would be nice if players stayed as loyal to clubs as the fans, but that's idealistic. Those days are gone and they're not coming back.
In the meantime, Rooney is stuck at United for at least another season, perhaps two if David Moyes takes the same stance in 12 months' time.
Most fans are willing to make the best of a bad situation and get behind their player for the good of the team. But they expect Rooney to repay the favour with his performances, whether his intention is to eventually leave for Chelsea or not.