O n a frigid day at Occupy D.C., Tim McFallon, the camp’s medic, stood chatting with a shivering blonde, gallantly offering her his warm pea coat.

“Let’s swap,” she purred as she discarded her own coat to reveal a long stretch of taut midriff underneath what could only loosely be described as a sweater.

“He’s my personal physician,” the young woman said of McFallon, giving him a meaningful glance. She then enveloped him in a gentle hug before drifting off, leaving the medic grinning in her wake.

As the Occupy movement enters its fourth month locally, it has spawned two full-service camps, more than 100 arrests and an ongoing constitutional debate over the right to free speech on federal land. But a combustible combination of youthful energy, enthusiasm for shared ideals and tight living quarters has given rise to something else: Romance. Lots and lots of romance.

More than a dozen couples have emerged after three months of outdoor living, including one pair who got engaged over the holidays. As with Occupy encampments on Wall Street and across the country, there have been many more casual hook-ups, bruised hearts and unofficial entanglements.

Medics at both D.C. protests routinely hand out condoms. At McPherson Square, there are also pregnancy tests — at least one of which has come back positive. Indeed, Occupiers are beginning to joke that a string of Occubabies may appear come June.

“You can’t spell ‘revolution’ without ‘love,’ ” said Michael Patterson, a 21-year-old protester who had a brief romantic involvement with another Occupier in the fall.

Last week, one of the resident anarchists at McPherson Square, Legba Carrefour, said he’d procured a used hot tub on Free­cycle.org, although it seemed unlikely that the National Park Service, which has jurisdiction over the two parks, would allow such a thing to be installed.

“It’s a bunch of people in their 20s, gathered in a public space with the express purpose of breaking the law. What do you expect to happen?” asked Rob Wohl, 23, a District resident.

Wohl groused that he had been “sexiled” from his tent one recent chilly night by an amorous pair seeking privacy, the Occupy equivalent of the old college dorm trick of hanging a sock on the door knob.

Sgt. David Schlosser, the public information officer for the U.S. Park Police, said that anyone caught having sex in the parks could be arrested and charged with indecent exposure or committing an indecent act. Occupiers are supposed to leave one tent flap open so that Park Police — who are assigned to the camps on a 24-hour basis — can monitor the area for illegal activity. More than 50 arrests have been made on park grounds for various offenses since October, including one charge of sexual assault, according to a National Park Service tally from December.

It’s not always rosy. Schlosser said about a half-dozen of the arrests involved quarreling romantic partners at McPherson.

Protesters at both camps said they have no internal rules governing sexual activity as long as it occurs between consenting adults and remains “inside the tents.” Protesters at Freedom Plaza — which has a slightly older cohort than the young rebels at McPherson Square — do ask for quiet time between 11 p.m. and 7 a.m.

Occupiers say that friendship forged during the movement can turn into something more in an instant, sparked by a lingering hug or a flirtatious glance. At McPherson, the exhausted and chilled protesters often fall asleep in group “cuddle puddles,” which are supposed to be platonic. Until they’re not.

Sariel Lehyani, 28, a District resident and protester, bonded with his girlfriend during a “lame” march to the Supreme Court, where they laughed together and decided not to get arrested. Amid such chaos, he said, it is good to have “an anchor . . . someone you can trust.”

Lehyani said he wonders about the permanence of such couplings in a place that has the heady atmosphere of sleepaway camp. (Or, at least, a sleepaway camp that can be raided by the cops with 24 hours notice.)

“These are the things you are thinking about: What’s holding you together? Is it camp holding you together, or do you just want to be warm at night?” Lehyani said. “In the real world, outside Occupy, do you have anything in common at all?”

Freedom Plaza protesters Mike Sheffer and Leigh Tatum met on a political discussion site on Facebook last year. In the fall, Tatum, 45, a hospice nurse from Alabama, persuaded her new friend to join the Occupy movement with her.

The two first shared a tiny tent as friends for six weeks, sleeping between a blanket barricade that Tatum had constructed. In such cramped quarters, they got on each other’s nerves a lot. Nonetheless, Sheffer, 54, an unemployed contractor from Vermont, began asking her for a good- morning kiss after a few weeks went by.

Her response?

“I said, ‘I would like to wake up in the morning and not want you dead,’ ” Tatum quipped. But then one day something changed in her heart. Finally, she kissed him.

“The look on your face was priceless!” she giggled, tucking her face in his shoulder as the two, swaddled in fleece and heavy wool, held hands in the camp’s information booth.

“It was so surprising,” he said. “I didn’t know what to expect.”

The couple has now moved into a bigger tent. A peek inside Thursday revealed an air mattress, two sleeping bags and a leftist pamphlet titled “How the People Got Their Groove Back.”

Then, over the holidays, Sheffer proposed. Tatum said she’d sleep on it. In the morning she said yes.

“I thought . . . full speed ahead!” she said.

They are the first to tell you they’re not a traditional couple. There’s no ring yet, and they’re not sure where they will live once they wed. But they are happy.

“It was really like a meeting of minds and hearts and souls,” Sheffer said. “It’s a great way to meet someone.”

Staff researcher Magda Jean-Louis contributed to this report.