I tried to find out more. Regarding supporter of IS/FSA in Scandinavia, there is an article which describes some of the groups: https://www.hate-speech.org/the-nordic-jihadists/Oxajil said:I've been watching a few interviews with Bashar al-Assad, and I thought he made an interesting remark in this clip. The interviewer asks him:
"According to SÄPO, the Swedish intelligence agency, returning jihadists – there are many here in Syria now – returning jihadists are the biggest domestic threat in Sweden today. Do you agree?"
Assad: "I wouldn’t look at terrorism as domestic or as regional. As I said, it’s global. So, if you want to look at Sweden as part of Europe or part of the Scandinavian group of European countries, you have to take into consideration that the most dangerous leaders of ISIS in our region are Scandinavian."
[...]
A year ago 300-350 Danes, Swedes and Norwegian were estimated to be involved in Syria:
http://www.thelocal.dk/20140924/new-fears-of-scandinavians-joining-islamic-state But that is only 10 percent of the total for Europe.
From available sources and taking the case of Denmark it turns out that at the end of 2014, 110 Danes were estimated to have been involved in Syria:
https://da.wikipedia.org/wiki/Dansk_deltagelse_i_den_syriske_borgerkrig
According to this page at least 17 Danes have been killed, see photos here: https://syrienblog.net/artikler/danskere-i-syrien/ If you look at the pictures of the now dead militants, two appear to be ethnic Europeans the rest have a variety of backgrounds.
At least one acted like IS is doing in the media:
http://www.thelocal.dk/20140923/danish-jihadist-poses-with-severed-heads-in-syria
Looking back on why they went, the FSA anti Assad stance in the local media might have contributed
The majority of Danish citizens who have been in Syria have fought with FSA and associate plus IS, a small minority including one woman has fought with the Kurds against IS. Below are some links in Danish which give such an example.
In an article about Danish Kurdic woman that later went to fight IS in Iraque, although she originally wanted to join the Kurds in Syria she is quoted as saying:
This does not mean that all youth get brain washed, she speaks about activity of some islamic groups in Denmark and what they do for some their followers, which motivates them to go and fight. Her statement that she would rather die fighting than fleeing, is understandable, even though she did not have to, considering what the follow up response in parts of the EU may be. I thinking of the prospects of a holocaust 2.0, but the people who end up in Northern Sweden around the Polar circle may also find themselves exposed.»The Islamic groups brain wash the young generation in Denmark and call them to go to Syria or Iraque and fight for a Caliphate. This is not the way of PKK and other groups. All the ones I know in the Kurdic areas, have told me that I should rather get an education and support the Kurdic issue politically. But right now, the Kurds are under attack, and if I travel down there, it is, because I personally want it. I would rather die in a fight, than die fleeing." says Joanna Palani, who herself has lived in the first years of her life in a refugee camp in Iraque.
Responding to someone, in Danish, who commented on the role of Denmark as a transit country for refugees to go to the promised land, Sweden, Palani writes, if I translate her position:
I think Vladimir Putin would agree that solutions have to be found, where the conflict is.https://www.facebook.com/photo.php?fbid=473327019504973&set=a.101865959984416.4681.100004830364257&type=1&comment_id=473331736171168&offset=0&total_comments=8&comment_tracking={%22tn%22%3A%22R4%22} said:"I think we [Denmark] should help, but as we are doing now is the wrong way. The problem is not DK but the war down here. So the solution should also be found here.. otherwise it is not an end."
For the record, and perhaps more for Scandinavian readers, there is an interview with Palani, although it is in Danish, but one can translate the text: http://www.dr.dk/nyheder/politik/valg2015/danske-joanna-kaemper-i-irak-mod-islamisk-stat and there is a documentary in Danish: http://www.b.dk/globalt/dokumentar-joanna-en-dansker-i-krig The government has not yet found out, if it okay for private people, like Joanna to fight against IS. http://www.politiko.dk/nyheder/dansk-kurder-risikerer-terrordom-for-at-gaa-i-krig-mod-islamisk-stat