What to do with the returnees?

[Husar]

The EU made us get rid of hanging for treason :(

Part of the reason we established the EU was to improve Britain.
No need to thank us.

Anyway - posing with severed heads means you were out there fighting, given the way IS fights I'd say this guy should be locked up or deported back to his new homeland.

The girl, perhaps, should be allowed to stay as afaik the "wives" of IS fighters have it only slightly better than their slave girls.

That's pretty simple, it sounds like you just assume typical gender roles.
In reality it is not that simple however.

These people have made colourful experiences in different countries where our laws do not apply, it is not up to us to judge them, we should see what we can learn from them and how they can enrich our society.