These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Noel Winters is the misogynistic and sadisticteenage leader of the gang of chavs living on the estate; he often abuses women for sexual pleasure while also engaging in regular acts of brutality, a lot of which he films on his phone. He and his gang regularly abuse Leonard to the point that the old man eventually tries to fight them with a bayonet - but is overpowered and kill by the gang, while they film his death on one of their phones. Although (whilst captured and being tortured by Harry) Marky admits that, whilst he and the others only really meant to scare Leonard, Noel was the one who ended up stabbing him. And Noel himself even urinates on the dead man's body. Later, during a riot on the housing estate, he is found hiding with help from his equally depraved uncle. Having been confronted by Harry (and also having found a female police officer trying to call for help), Noel's uncle tells him to strangle the officer, and Noel takes pleasure in sadistically strangling the woman - and actually encourages her to struggle for her life, as he watches her die!
One-Scene Wonder: Sean Harris is onscreen for ten minutes max. He doesn't just steal those ten minutes, he points a gun at the clock and demands those minutes be put in a bag before speeding off in an unmarked car.
The Woobie: Marky isn't all that bad really, and if he were it wouldn't make the stuff that happens to him any less wince-inducing. He's also the Butt Monkey.