They used to be football hooligans, fighting each other on the terraces and in the streets.
Now, two groups of “football lads” have got together to combat extremism – but in very different ways.
The Democratic Football Lads Alliance claims to be against all forms of extremism – but critics say it peddles far-right and Islamophobic ideas online and on its marches.
Worried football fans created Football Lads And Lasses Against Fascism in response.
No longer involved in football violence, men from both groups spar online and put up stickers around grounds to mark their territory.
Produced, filmed and edited by Lucy Proctor
For more on the DFLA and FLAF listen to this edition of 5 Live Investigates.