Again - absolutely no chance.
Lille itself is a very friendly city. It's twinned with Leeds by the way. But don't let that put you off because of Leeds United
[Leeds the city is also super friendly and welcoming if you don't go near the football fans on a matchday.]
It's cosmopolitan. It has a massive student population (biggest outside Paris) and lots of foreigners work there, plus its a business hub for northern Europe. It also has a huge bar and gastro culture - bars and restaurants everywhere.
They're very proud people
(Flemish heritage, not French) and they love their football but their not violent at all. I imagine it would be a bit like going to Goodison as an away fan - banter and laughs then hostile for 90 minutes, then banter and laughs.
My first year there they did the double, league and cup, and they went for the French cup final to Paris, and beat Paris St Germain - who they hate. All came back so happy, and not a spot of trouble while in Paris.