Tilda Swinton acts as a strong heart to this film, having to convey many states, from travel-writer and explorer, to mother, to the vilified mother of a monster after her teeneage son commits an atrocity.
Most of it is portrayed with exceptional skill. Swinton excels at the brittle and shattered mother struggling to get by amidst the torrent of hate and judgement heaped her way every day, but she's always been good at playing the wounded or the outsider. Playing Kevin's unwilling mother - unable to bond with her baby, and unable to get him to warm to her either - she's also very good. Where she utterly failed to convince me was as the 'carefree explorer' and travel writer who lived for adventure. In those segments she never feels anything other than a performer going through the motions. Luckily they're sparse. However, they're also quite chilling. The films opens with her explorer self crowd-surfing at the 'la Tomatina' Spanish event where crowds pelt each other with ripe tomatoes, and the film plays the crowds writhing and covered in red with eerie hints of screams and panic echoing in to echo the future atrocity Kevin will commit. It's a memorable opening, and the film remains as visually strong throughout.
Much praise has been heaped upon Ezra Miller for what is undoubtedly an extremely assured and powerful performance as the teenage Kevin, but as much credit should be given to Jasper Newell playing the 6-8 year old version who actually carries most of the running time. It's during the earlier years that we see Swinton's character struggling to coax any reaction except cold emnity from her child, as if he senses the fact that he was unwanted, and he reacts in kind.
These sequences are a masterful power play of manipulation, passive aggression and emotional violence, with the oblivious father played by John C Reilly breezing into them to be greeted by a suddenly charming and chirpy child.
The film is convincing in the emotional reactions of all involved, and there are emotionally shattering and true-feeling moments in the aftermath of the tragedy. The student who doesn't hold a grudge despite his own hardship, and the co-worker who thinks he can take advantage ring especially surprising but true.
As the teenage Kevin, Miller is as malevolent, manipulative and charming as a cobra, sociopathic in the extreme. Perhaps the strongest moment of the film is the scene where his mother has made exceptional efforts to try to heal their relationship only for him to cut her down with such a stinging, withering and contemptuous verbal barrage that you feel that anyone in her shoes would be equally struck dumb with shock.
While the film tastefully avoids showing much of the actual violence, it remains an emotionally brutalising ride, and puts a surprisingly emotional case forward, implying that while she may have been instrumental in the formation of a monster, the mother was suffering just as much as everybody else.