I defined the Green Tribe as being "home to the pro-EU unionists who were perfectly happy inside both unions (28% of voters) [mnemonic: green for hope, because they will hopefully vote Yes next time]".
Members of the Green Tribe typically voted No to independence but Remain in the Brexit referendum. They also typically vote Lib Dem or Labour (or in some rarer cases Green or Tory). This means that most of them have been used to being in power for a while, and seeing the SNP take over in Scotland and then losing the Brexit referendum must have been a shock to many of them, which means they're now angry and confused, in many cases even passive-aggressive.
The interesting thing about this Tribe is that it has just lost its ancestral land. The Brexit referendum was won by Leave, and there's no signs that the UK as a whole will reverse that decision. As a result, they now have to choose between their two beloved unions, the British one and the European one. If they go for the former, they'll effectively join the Red Tribe, and if they opt for the latter, they'll become part of the Blue Tribe instead.
What we don't know is how the Green Tribe will split. Those members who weren't very strongly attached to the EU, perhaps only supporting it because the tribal elders told them to, will probably remain faithful to the UK and will thus become Reds. On the other hand, those who mainly supported the UK because they saw it as a vehicle for internationalism will soon realise that the Blue Tribe members tend to share their goals, perhaps helped by yesterday's #WeAreScotland tweets.
Obviously joining the Blue Tribe is only attractive to Green Tribe members if they think it's a safe way to escape the newly xenophobic rUK and remain within the EU. If a new independence referendum gets put on the back burner, there won't be anything of interest for them to find in the Blue lands.
We independence supporters need to be very welcoming to Green Tribe members looking for a new home, and we need to stop ourselves for reminding them that "we told you so", tempting as it is. They'll bring a new perspective on things – for instance, they might be nostalgic for the liberal and internationalist UK of yesteryear, and waving Saltires might enthuse them less than other independence supporters – but I'm sure that'll do us no harm.
If we manage to win over a significant proportion of the Green Tribe, we'll win Indyref2 easily. If we don't, it'll be a sair fecht. That alone should be enough to convince everybody to welcome them with warmth and patience.