Despite the tribal passions on each side of the Wear-Tyne divide, players -- even locally bred ones -- have always been willing to turn out for both Sunderland and Newcastle United, sometimes making the direct switch between clubs.
The latest example sees Jack Colback, from staunch Newcastle-supporting territory north of the Tyne but a product of the Sunderland youth system, finally joining the club he supported as a boy.
Many Sunderland fans will be disappointed, inevitable as the departure became once his contract ran out and it became clear he felt he could do better than the kind of renewal terms Sunderland were proposing.
Colback was a model professional. He wholeheartedly overcame childhood allegiance to become a dependable fixture in red and white, to the extent of angering Geordies with his exuberant celebration of a superbly taken goal to round off last season's 3-0 win for Sunderland at St James' Park.
Soon enough, he will feel just as much at home at Newcastle as many players of the past whose names fans of both clubs could easily rattle off without the need to consult history books.
Do not think for a second, however, that all footballers with local connections have found it comfortable to wear the "wrong stripes."
LEE CLARK
Former Sunderland boss Peter Reid once said it was not until a fifth bottle of champagne had been uncorked that he could get Clark, a Newcastle fanatic, to leave St James' Park for the Stadium of Light in 1997. The move worked well as Clark showed exemplary resolve and midfield flair to help Sunderland to a runaway promotion as champions in his second season.
But that was that. Newcastle reached that season's FA Cup final and Clark was seen with Magpie pals at Wembley, wearing a "Sad Mackem B------s" T-shirt. Reid promptly excluded him from the squad and he was shipped out to Fulham. Some believe an element of planning was involved, as Clark was convinced he could not bear to play for the enemy in derby games back in the Premier League. As if to atone for his past disloyalty, Clark returned to Newcastle for a brief second spell at the end of his playing career.
ANDY COLE
A goal machine for Newcastle, past his best-before date for Sunderland, Cole offers a striking example of contrasting fortunes. At Newcastle, he scored for fun, his haul of 68 goals in 84 games only marginally inferior to the ratio achieved by an old-time Tyneside hero, Hughie Gallacher, but better than those of Toon legends Malcolm MacDonald and Jackie Milburn. By the time he reached Sunderland, playing under his former Manchester United teammate Roy Keane, his powers had faded; Cole played just seven times and did not score .
POP ROBSON
Sunderland-born but a prolific striker for Newcastle -- 82 league goals in 206 senior appearances from 1962 to 1971 -- Bryan "Pop" Robson went on, after a successful move to West Ham, to begin the first of three spells at Sunderland. His hometown club were not disappointed: each period produced goals, 60 in all, and he later served as caretaker manager and chief scout.
A revered name in English football but mentioned more fondly by Sunderland than Newcastle supporters. The celebrated "clown prince of soccer" -- an engaging character who provided a brilliant, if often infuriating, mixture of magical skill, rebelliousness and tomfoolery -- had nearly two turbulent years at St James' Park before embarking on his career-best stint, with 101 goals in 348 Sunderland outings from 1948 to 1957.
His brushes with football's establishment limited his England chances to five caps just as his confrontational attitude had soured relations with Newcastle's management. "I'm not biased when it comes to Newcastle," he famously later said. "I don't care who beats them."
BOB STOKOE AND STEVE BRUCE
Two Newcastle supporters with mixed experiences of managing Sunderland. Stokoe, a playing hero at St James' Park, has a statue outside the Stadium of Light to honour his outstanding feat in taking Sunderland from the old Second Division to glory in the fairytale defeat of then-mighty Leeds United in the 1973 FA Cup final.
Bruce, despite achieving a respectable 10th-place finish in the Premier League, is remembered more for subsequent, somewhat paranoid, whinges about being driven out of Wearside because of his support for Newcastle.
MICHAEL CHOPRA
Played without great distinction in just 21 senior games for his native Newcastle as his first professional club but, after loan spells and a superb season with Cardiff City in the Championship, scored some important, relegation-avoiding goals for Sunderland. He was, however, accused of deliberately missing a fabulous chance to secure victory at Newcastle, instead overhitting a pass to Kenwyne Jones.
Chopra flatly denied intent in what is routinely called "that miss," saying he simply made a poor choice. But the suspicions are established in Mackem folklore, with more than a few Geordies happy to share them.
Supporters' reluctance to find Chopra's protestations of innocence persuasive stands with the Lee Clark gesture and Steve Bruce's bitterness as powerful evidence of the intensity of the regional rivalry. Colback will have to prepare himself for the closest of scrutiny as he begins the new phase of his career.