One plays a young architecture student dying of cancer while acting as the primary caretaker to an autistic brother; the other an unmarried middle-aged lawyer with fertility issues who desperately wants to have a child.

On the surface, they’re as different as two psychotherapy patients could be. And yet the storylines of both Alison Pill (April) and Hope Davis (Mia) succeed in what “In Treatment” does brilliantly — presenting universal themes that transcend particular individual problems.

“There’s something universal about her situation,” posits Pill (“Milk,” “Dan in Real Life”), whose character sweetly begs therapist Paul Weston (Gabriel Byrne) for the love her parents never gave. “It’s interesting to see how different people relate to different aspects of the story, whether it’s having cancer or having a brother who has autism or having to ask for help, which I think is hard for so many people.”

Davis, fresh off a Tony nom for her work in “God of Carnage,” looked to friends when prepping for the role of a deeply remorseful woman whose life has fallen short of all youthful expectations. (Mia blames Paul, who was treating her at the time, for an abortion she had long ago.)

“The character interested me because what she was going through made so much sense,” says Davis. “I have friends where you see that nothing is going right in their lives and they’re putting up roadblocks. With Mia, at 43 years old, her life has been in her hands for a very long time. You wonder, is she going to get anywhere, or is she going to live this way for the rest of her life?”

So personal was the material — “The scripts were so rich and complicated,” Davis says in praise — that the experience of the shoot was nothing short of heady.

Adds Pill: “It was exhausting to have it on the back of my mind all the time. The intensity of it was disturbing.”

For Pill, screening these completed episodes has proved therapeutic.

“On Sunday nights I go over to my parents for dinner and we watch our therapy sessions,” she says with a soft laugh. “We discuss.”

What do you like most about your character?

Davis: “How unashamed she is to be really ugly. She’s got this vulnerable side mixed with her killer lawyer side. She kind of lets it all hang out, and it’s not pretty.”

Pill: “She’s incredibly strong and unbending in a lot of ways but is trying to do it better than she’s learned so far. I like that she’s trying to figure herself out despite her best threats not to.”