Fire when it comes to passion; ice when it comes to decision-making. With only four points separating the teams, neither group sees even a remote chance that the cup's destination has been settled by Glasgow Warriors' 20-16 triumph at Murrayfield on Boxing Day.
That is just one element of the common ground between the groups of players. Among the others is the understanding that Edinburgh played the better rugby for more of the match; there was an element of luck involved when they failed with two scoring chances - these things tend to even themselves out over time - and that discipline played a key role in the result with Duncan Weir winning the penalty shoot-out against Greig Laidlaw 5-3.
As Cornell Du Preez, the Edinburgh flanker, put it: "In these games, it is discipline that counts and both teams got yellow cards, so it is something we have to work on. We said before the game we have to have fire in the belly and ice in the head; sometimes you lose it in games like this. It is the team that has the best composure that will come through."
Glasgow had just enough ice to turn their only chance into the match-winning try for Stuart Hogg, one of those who had demonstrated the fiery side of the clash when he and Tom Brown, the Edinburgh wing, tussled on the touchline and ended out pulling each other over the advertising hoardings. Edinburgh in contrast scored early and had two chances they did not take, one dropped by Jack Cuthbert, the full-back, and the second when Du Preez himself was gang-tackled inches short of the line.
"I was pretty close but I just could not get there," Du Preez said. "Our first half was very good but we are very disappointed in our second half, which was poor. We can build on our our first half, though. I don't think the stuff they did mattered that much. We are just disappointed in ourselves, especially at the breakdown; that is something we need to work on. We need to look at ourselves.
"The way we played in the first half: if we can keep that going for 80 minutes we can get the four or more points we need next week. You don't need extra motivation for these derby games."
It is reasonable to assume most of the Edinburgh players on duty at Murrayfield will be given the chance to have their revenge at Scotstoun on New Year's Day. One of the big differences between the clubs being Alan Solomons has a clear first-choice player in most positions, tries not to rotate his team and only uses his replacements when he feels he has no option. For Glasgow, it is doubtful if even Gregor Townsend, the head coach, knows his first-choice XV and, in emptying the bench during the first leg and pointedly praising their contribution to the come-from-behind win, he was sticking to the pattern of his coaching career.
So rest assured, there will be changes in the Glasgow side, some possibly enforced by the head knocks suffered by Tommy Seymour and Ruaridh Jackson, some simply because under Townsend's restless, ever-changing regime, only an injury crisis can keep selections stable. He undoubtedly feels vindicated, at least as far as his use of the bench is concerned: seven of his eight replacements were on the field by the time Hogg gave them the lead; Edinburgh used only two permanent replacements, and only one before Hogg scored.
It led to at least one memorable sight: Ryan Wilson,the No.8 spent most of the second half playing centre, after injuries in the backs left his side out of specialist options. "He is a great rugby player and fitted in well," said Alex Dunbar, who had to nurse him through the experience as his midfield partner. "We were talking to him all the time and making sure he was in the right place.
"We can be very proud of the boys. Defensively, we put in a big shift, especially in the second half. All the forwards got round the corner and tackled: Tom Ryder, Tim Swinson, all the props as well put in a massive shift. We're really happy to get another win.
"We have not quite been at the races the last couple of weeks as a few mistakes have crept in so it was positive to get the win but we know how hard it is going to be next week. Edinburgh will come across and it will be even tougher. We knew the way they wanted to play: they would try to make yards, be dominant and their big ball carriers would try to get over the gain line. We have things to work on for next week, they played well."