Everything about Mark Ruffalo is slightly harried and disheveled. It added humanity to his Hulk and made him a lovable, irresponsible cad in The Kids Are All Right. So portraying a man recovering from a manic-depressive breakdown while raising two willful preteen daughters seems like a perfect fit for the actor. In Infinitely Polar Bear, Ruffalo plays Cameron, a Boston husband who finds himself becoming the primary caretaker of two daughters after his wife, Maggie (Zoe Saldana), leaves to New York to find work.
A man who seems wholly unable to care for himself is now responsible for the well-being of two girls who have been forced to grow up too soon. Cameron's rapid-fire, curse-filled language and overeagerness for just about everything in life both terrify and delight his children. Neighbors in their Boston apartment building do all they can to avoid his innocent yet wholly inappropriate gestures of friendship. The girls' mother returns home on weekends to survey the havoc with a look of fear and exhaustion.
Ruffalo jumps into the manic nature of Cameron with a gusto that at first is quite entertaining, but eventually begins to feel tiring. (The one calming force in the film, the girls' mother, has too little screen time to balance Ruffalo's character.) The thing about manic depression is that it's not all manic all the time. This film spans the course of a year in the life of this family, and rarely in the film is Cameron not bouncing off all of the walls. The cumulative effect gives Cameron an immaturity that doesn't do justice to the full lives of bipolar adults. Having many adult friends with bipolar disorder, I can attest that there are highs and lows and so very much in between. While they may often struggle with the emotional extremes of their disorder, they are still adults.
Infinitely Polar Bear is actually based on a true story from the life of the writer and director, Maya Forbes, whose father lived with bipolar disorder. It is easy to see that this film was written with love and care, but it feels more like a remembrance of the loudest moments of Maya's childhood instead of a complete and realistic story. The yelling matches, the broken-down cars, the moments of embarrassment—those are the stories that we tell at family gatherings, but it's the little moments we don't mention that make a life, and a film. 
