“Cyrus” is a love triangle with a twist, in an ironic atmosphere.
John C. Reilly pla\ys John, a man who’s admittedly in a downward spiral.  His ex-wife, Jamie (Katherine Keener), has moved on, and is preparing to marry Tim (Matt Walsh), who has little patience for John’s continued emotional dependence on Jamie.  John says he’s a freelance editor, but we don’t really see him working much.  Jamie insists that he come to their engagement party, just to get him out of his apartment, and maybe out of his funk (obviously, her former love for him has distilled to mere pity, but she still cares for him, in a condescending kind of way).
John relents and comes to the party, but is obviously uncomfortable in unfamiliar social situations, and his lame attempts to even engage women in conversation are met with devastating disinterest.  Finally, he hears a song he likes on the stereo, turns up the music, and just starts dancing, and Molly (Marisa Tomei) responds to his pitiful requests for someone to please come out and dance with him, and somehow in his unfettered zeal she sees some potential passion that’s been lacking in her life.
At first, she doesn’t tell him anything about herself.  But John is so grateful for her interest that he cannot suppress his natural curiosity, and so he follows her home, and there he meets Cyrus (Jonah Hill), her grown son.  He seems to be either stunted emotionally, not quite all there, or pathologically immature, and, it turns out, maybe it’s all three.  Cyrus and Molly are so intimate emotionally that he calls her by her first name, rather than “Mom,” and they spend inordinate amounts of time together, engaging in the kind of playful, easy affection that would feel entirely appropriate if he were, say, six years old.  But now it looks kinda weird.  And John thinks so, too.  But when he tries to talk to Molly about it, she seems oblivious to the potential difficulty, wanting, understandably, for her new boyfriend and her only child to like each other, and unwilling to define for either one of them what the boundaries ought to be.
There’s some really awkward family situations here, and some frank sexual humor, though no real gratuitous nudity, and hardly even much physical intimacy.  This weird love triangle puts a lot of pressure on these three actors to carry the whole movie, without the aid of a complicated plot, or the normal whiz-bang special effects of modern big-budget films, or any chase scenes, or any evil-villain-out-to-blow-up-the-world kind of dramatic effect.  There’s just the clumsy reality of these strangely stark people, trying to awkwardly figure out how to be individually warped and jointly dysfunctional, and somehow make it all work.  Feels like real life to me.
Dr. Ronald P. Salfen, Pastor, Grace Presbyterian Church, Greenville , Texas