The brothers are busy either being witnesses to ruin or the perpetrators of ruin. Blood is spilled. Other bodily fluids are, shall we say, released. Captives are taken. Revenge is sought.
Unnecessary force is used.
Foul language is used. Insults are hurled. All of this takes place at the slightest provocation. Some of the other Glaswegians are just as hellbent as the brothers on leaving their mark on the world. If, that is, there are really this many people in Glasgow who are this nasty.