There’s a theory about the reason people act the way they do.

There’d be no love, no war, no meaningful emotion, says this theory, without a certain looming inevitability that hangs above our existence. All living things eventually die — but part of what distinguishes humans is that they’re fully aware of that fact.

In a way, every movie — every human interaction — must deal with mortality in some small way. Some scripts do their best to ignore it, but realistic characters always have their actions grounded in a finite existence. Others face the problem head on, opting for a literal look at the effects of death. And then there’s a third subset that wrap their musings on mortality in a story about something else: divorce, say, or a game or chase that’s ending.

This week’s movies, “It’s Complicated” and “The Imaginarium of Doctor Parnassus” each address mortality, one directly, one indirectly. But the two are interesting in that both introduce another question into the equation: What happens if death isn’t final? When is the end not really the end?

“It’s Complicated” is a romantic comedy detailing the love triangle of three wealthy, attractive, aging people played by three wealthy, attractive, aging actors. Jane (Meryl Streep, “Fantastic Mr. Fox”) runs into her remarried ex-husband of ten years, Jake (Alec Baldwin, “30 Rock”) at the high school graduation of their third and final child together. After a few drinks, and then a few more, they find themselves reminiscing about the time they shared together, and their trip down memory lane cul-de-sacs into a hotel bedroom. At the same time, Jane is slowly but surely leading on, and falling for, the architect creating the new addition on her house. That man, Adam (Steve Martin “The Pink Panther 2”) has also been through a divorce and is loath to enter any relationship where the woman’s relationship status is in doubt.

The plot is average, as is the acting and directing (Nancy Meyers, “The Holiday”). But what saves the whole endeavor from completely fading into pink-trimmed genre oblivion is the quiet edge of desperation not usually present in airy, trodden romantic comedy.

Not only does the “divorce as death, love as re-birth” metaphor run throughout, but the characters’ ages are also a constant point of reference. Take, for instance, Jake’s flagging reproductive capabilities, Jane’s contention that her body looks better laying down than standing or any of the dozens of other allusions that made me vaguely uncomfortable but probably caused older viewers to nod slowly and sigh. Jane is lonely, dead to love and to experience that important rebirth she must figure out which of her suitors most understands her — the one she loved for twenty years, or the one that knows exactly what she’s been through.

So age, death and rebirth are central to, yet hidden within the plot of “It’s Complicated” even before a creased, tired Steve Martin enters the frame. “The Imaginarium of Doctor Parnassus” makes no such attempts at concealing its themes of mortality and resurrection, falling squarely into that second camp of movies that design their plot around the fear, familiarity and immovability of death.

Director Terry Gilliam (“Tideland,” “The Brothers Grimm”) begins his surreal fantasy with an interesting trick in the opening credits where names are shown as if they appeared on a reflective surface. However, upon closer inspection, the fonts on the mirrored images differ. That’s just the start of the film’s complicated look at dualities: rich vs. poor, antique vs. modern, love vs. lust, right vs. wrong, they’re all there. But the biggest question posed by “The Imaginiarium of Doctor Parnassus” is a more vexing choice — Which, in the end, is more damning: death or eternal life?

Doctor Parnassus (Christopher Plummer. “The Last Station”) would probably argue the latter. Through several deals with a man (who is very likely The Devil) named Mr. Nick (Tom Waits, “The Book of Eli”), Parnassus has gained everlasting life, but at the expense of his daughter on her sixteenth birthday. On the eve of that milestone, the Doctor makes another deal with Nick to stave off her capture. The two will race to convert five souls to their cause: Doctor Parnassus for the importance of imagination, Mr. Nick for the power of fear. With the help of a ragtag crew and a mystery man rescued from the noose (Heath Ledger, “The Dark Knight”), Parnassus must convince five to change before the clock strikes midnight on his daughter’s eternal soul.

Unfortunately, for all the film’s explicit, planned references to death, one plot twist that could not be avoided was Heath Ledger’s death at age 28 during filming in 2008. However, after a brief hiatus, Gilliam returned to the movie, substituting Johnny Depp (“Alice in Wonderland”), Colin Farrell (“Crazy Heart”) and Jude Law (“Repo Men”) in Ledger’s place. Ledger’s demise was undoubtedly tragic, and in the context of the film it serves as a brutal real world backing to the fantasy film’s fixation on mortality.

Facing our mortality might be uncomfortable, but it’s a major factor in human behavior. It seems a long way off, but the bittersweet truth is one day, after we’ve been through divorce, seen our bodies sag, struggled with fertility or made a bargain with our own personal Mr. Nicks, each of us will have no choice but to nod slowly, sigh and ponder a personal rebirth.

Lin Weeks is a sophomore majoring in finance and marketing. Upset with his omission of the DVD you were most excited about renting this week? Vent at [email protected].