One of my friends from the IDD and Facebook, an Iddiette named Susan K, wrote to me after I posted "Brothers In Arms" (about David 'Callan' and Robert McCall 'The Equalizer' being brothers):
"Everytime I see Callan I think you're talking about G.Callen from NCIS:LA"
So I visited the Wiki for 'NCIS: Los Angeles' (every show seems to have a Wikia!) and learned this about Agent G Callen:
G. Callen's formative years were spent in the foster care system until he attained majority at the age of eighteen. He possesses little knowledge about his birth and infancy, this is attested to by the fact that not even he knows what his given name is apart that it begins with the letter "G." In the episode Pushback (1.7) we learn that Callen lived in more than thirty-seven foster homes starting from the age of five, the longest he stayed in one of them was only three months.
The argument could be made that G (who was born in 1969) is the illegitimate son of David Callan - that his last name was misspelled on his birth certificate or on the forms that entered him into the foster care system (presumably California's).
The timeline of his birth does make it possible.....
There'd have to be some theories tossed about:
that G's mother had an affair with David Callan, either in Britain or whenever he might have been in the United States (perhaps on assignment in Washington with Toby Meres?).
that they must have broken up before she knew that she was carrying Callan's child.
that after a few years she knew she couldn't care for him anymore, or she was unable to do so because of circumstances beyond her control, and that's why he was placed in foster care.
that blood will out - G Callen's natural talents in the field could mark him as being the son of David Callan. (A notion that sounds very Wold Newton....)
I'm just going to toss the idea out there as a possibility, but not one Toobworld Central is ready to commit to. Things might be different if William Zabka, who played Scott McCall on 'The Equalizer' had any other TV roles which could be considered an alias for Scott. Then we could run with a full family tree, maybe even taking it back into the past beyond Captain William McCall, or even far into the future with any potential McCalls on the various 'Star Trek'/'Babylon 5' shows.
But according to the IMDb, Zabka hasn't done any TV since 'The Equalizer'. (But he has kept mad busy with movies, even if most of them look like they're direct to video.)
So for now, this will be just a small addendum to the theory of relateeveety about Robert McCall and David Callan.....
And it will be blown all to hell once the show finally decides to do a show that explores G Callen's birth and infancy.