Former Mayor Willie Brown’s decision to buy into Oakland a few years back has led to a battle royal with the very guy who steered him to invest there — Brown’s onetime friend and building-industry powerhouse Joe O’Donoghue.

The feud between the men who barely a decade ago were the embodiment of San Francisco clout comes complete with dueling lawsuits and even a temporary restraining order meant to protect Brown’s wife from “elder abuse” by O’Donoghue.

The Irish native has been out of the news for a while, but longtime residents of San Francisco should remember him well. In the explosion of residential loft construction that dominated San Francisco real estate and politics during the dot-com days, O’Donoghue’s Residential Builders Association was a feared force.

The group spread tens of thousands of dollars to state and local politicians, including to Brown, a Chronicle columnist who as mayor appointed O’Donoghue allies to key jobs in the city’s planning apparatus.

O’Donoghue eventually left the RBA, and in recent years has largely focused on his private business affairs. But judging from his dispute with Brown, the 78-year-old ex-builder hasn’t lost any of his bark.

At the heart of the dustup appears to be a years-old plan to build a condominium tower next to an 11-story apartment building on the shores of Lake Merritt that Brown invested in in 2006 — and where his wife, Blanche, and their two adult daughters now live. Over the years, the fight has gotten both very political and very personal.

Just this past week, an attorney for the Browns — who, though legally still married, have long lived largely separate lives — asked an Alameda County Superior Court judge to issue an order that would bar O’Donoghue from “interfering’’ with their rights as property owners at the Lake Merritt building. The Browns sought the temporary restraining order after O’Donoghue changed the locks on the 79-year-old Blanche’s storage unit and moved the building’s garbage bins, in what they charge was an act of elder abuse.

The Browns’ court action — which also included a lawsuit seeking unspecified financial damages for emotional distress — came a month after O’Donoghue’s longtime companion, Sherrie Matza, filed the first legal shot. Her suit accuses the Browns and Victor Makras, a real estate executive and president of the San Francisco Retirement Board, and his wife, Farah Makras, of multiple partnership breaches involving the Lake Merritt apartment building they jointly purchased. O’Donoghue is not a partner in the building.

“It’s going to be the shootout at the O.K. Corral,” he promised.

“You can’t write this script,” countered Willie Brown, who has pretty much seen it all in more than half century of public life and is still at a loss to explain how his once-chummy relationship with O’Donoghue turned into a sour soap opera.

Troubles started when a plan by the Browns and the other owners to donate a 30,000-square-foot garden at the rear of the property to the city in exchange for tax credits went sideways.

So Roy Guinnane, a former San Francisco Building Inspection Commission member who is also a partner in the building, teamed up with San Francisco builder David O’Keefe and Matza on a plan to instead develop condos on the garden site — with O’Keefe paying $3.6 million for the Browns’ and Makrases’ share of the yard.

O’Donoghue says early on the Browns opposed the proposed tower, saying it would ruin the views from their own building.

The group is still trying to get city approvals for their 30-story tower, known as Emerald Views.

Now O’Donoghue says the real rub is that neither the Browns nor the Makrases will sign off to allow the front of their apartment building to be used as a construction staging area for the new condos.

“That’s the issue,” O’Donoghue said.

It’s also apparently what’s driving the lawsuit that O’Donoghue’s live-in partner filed against the Browns and Makrases — which accuses Willie and Blanche of doing all sorts of remodeling to their units and the building’s lobby without proper permits and authorization from their fellow owners.

All of which brings us to the Browns’ countersuit, accusing O’Donoghue of elder abuse and infliction of emotional distress. It was filed just days ago after O’Donoghue changed the locks to Blanche Brown’s storage locker and moved the building’s garbage bins — allegedly in a fit of pique over the mess created by her contractors. On Thursday, Judge Evelio Grillo issued an order giving O’Donoghue 24 hours to return things to the way they were.

O’Donoghue tells us that’s just Round One, and he’s not done fighting to prove all the injustices perpetrated by his old friend Willie Brown and his wife.

“We drew a line in the sand, and the war is on,” he said.

San Francisco Chronicle columnists Phillip Matier and Andrew Ross appear Sundays, Mondays and Wednesdays. Matier can be seen on the KPIX TV morning and evening news. He can also be heard on KCBS radio Monday through Friday at 7:50 a.m. and 5:50 p.m. Got a tip? Call (415) 777-8815, or e-mail matierandross@sfchronicle.com. Twitter: @matierandross