Like its title character, “The United States of Tara” has multiple personalities. At times it’s a comedy, poking fun at the zany situations Tara’s multiple personalities get her family into. At other times it tries to be a suspense-driven thriller—its most annoying personality, and one that thankfully only emerges in the back half of the last season. But its true personality, the one that’s most developed and nuanced, is an emotionally-grounded, character-driven family drama about how the Gregson family manages to stay whole despite—and sometimes because of—Tara’s dissociative identity disorder.

I mean, when it wants to be, this show can be dark. I’m not talking about the creepy, unsatisfying serial killer arc in the third season. I’m talking about moments like the one when Marshall Gregson sets the family shed on fire to get back at T, one of Tara’s personalities, for making out with the guy he’s crushing on. Or when Charmaine, Tara’s sister, tells Tara she doesn’t want her near her newborn baby in case she transitions into another personality and hurts the baby. These moments are all driven by believable emotion, and it’s hard not to feel a pang of sympathy for Tara and her family when watching.

Of course, that only makes it all the weaker when the show’s other personalities emerge. After all, it might be funny to see Buck, Tara’s southern hick personality, come out and crack a few jokes, but once you’ve seen the emotional trauma he puts the family through when he starts a relationship with a local barkeeper, his appearances become much less funny. It’s a difficult line to toe, and oftentimes “United States” ends up on the wrong side.

The character development drives this show, which is why when the plot takes center stage it feels a little lacking. All of these characters are distinctly human; they all have their own problems: take Kate, the other Gregson child (played by Brie Larson, who I’m happy to see again after first meeting in “Scott Pilgrim vs. the World”), maturing from a petulant teenager to a mature adult. She changes her mind as quickly and often as Tara changes her personality, but unlike Tara, she grows by leaps and bounds in an evolution that sometimes feels rushed, but never forced.

When it comes to TV, I’m often invested more in the story than in the acting; bad acting will pull me out of a show, but good acting tends to just blend in to the background for me. But it’s impossible to talk about “United States” without Toni Collette, who plays Tara, and the way she effortlessly pulls off not one, but eventually eight different characters, each distinct from one another in dress, voice and manner. Tara is completely different from T, and both are completely different from Alice, the ‘50s housewife, and so on.

Though it stumbles a few times, eventually “United States” manages to end on an emotionally strong note. In fact, you’d never guess that the third season finale wasn’t originally written to be a season finale. Things in the Gregson family still aren’t good, but it’s better that way. I’m a sucker for ambiguous endings, after all, and after years of getting worse, it doesn’t make sense that it would just snap back to normal. It’s as close to a happy ending as the family can believably get, and after three years of putting up with the discordant states of Tara, boy does that family deserve it.