I think that since Merritt Buttrick was gay (and, sadly, died from AIDS), it's been widely speculated David Marcus was gay.
Which is fine, but not canonical.
True, it's not canonical, but in the original print of TWOK, there is clearly an attraction between David and Saavik.
Also, the original plan for TSFS was that Spock and Saavik have sex and that she subsequently became pregnant. In an interview I read before TVH, DeForest Kelly joked that McCoy would have trouble delivering Saavik's child because of its ears.
That was the plan, to plant a seed (LOL!) for a future ST film. It's the same reason for the "Remember" line in TWOK. Originally, Bennett and Meyer didn't know what they'd use that for, but they put it in there just in case. It's the same thing with Spock and Saavik having sex (and I think it's obviosu that it did happen, they were engagin in Vulcan foreplay and Spock was going through Pon Farr, that was the intent of that scene).
Why did Saavik remain on Vulcan in TVH with Amanda? Because she was with child. In the end, they chose not to follow up on this storyline in the last two original cast films. It's a real shame, but, in my mind anyway, I don't see why it couldn't have happened anyway. Add in that line in the TNG episode Sarek about Picard attending Sarek's sons wedding to the above facts and the intentions of Nimoy and Bennet with TSFS and TVH's screenplays and there's circumstantial evidence that Spock knocked Saavik up.
I wish they could've done something with that, but Shatner did his own thing with TFF (he gave Spock a brother instead of a son), which sucked and they had too much other stuff in TUC. I doubt we'll see Spock's son or daughter in XI, but, again, there's enough evidence for me, along with the writers' intent, to believe Spock had a child with Saavik.
