I always took it for granted that when they were stuck on the Genisis planet and teenage Spock was undergoing the Pon-Farr and Kirk's son goes off to fight the Klingons that Savvik had sex with Spock. Does anyone doubt this?
Of course they had sex. Supposedly, in an early version of STIV story, Saavik was pregnant with his child.
I think the filmakers smartly left this open to interpretation, but playing it more on the safe side. My interpretation is that they did not have sex. There just wasn't any real indication of that. I think Saavik simply helped him center his chi. (Is that what the kids are calling it these days?)
It's definitely implied, but not stated outright. However, the cues (inherited from classical Hollywood) are pretty obvious. I voted "They very well might have done," but should have gone for the "of course they did" choice." What isn't so obvious is why Saavik decides to stay on Vulcan in STAR TREK IV: THE VOYAGE HOME. Is she pregnant with his child, as early script drafts indicated? It's left up in the air, but it's definitely possible.
Capt. Spock: "I did not have sexual relations with that woman." Or in other words...of course he did.
It's subtle enough to not be in your face about it, but I think the idea is that they had sex. I think the more subtle, implied but not spelled out route was the right way to go.
If I remember the novelization correctly, Saavik was getting lucky more than Kirk in II-IV -- she not only helped Spock through pon-far, she was banging David and, before that, Peter Preston. Which actually raises an interesting possibility -- if Saavik was pregnant in IV, maybe it wasn't Spock's kid. Maybe Kirk has a quarter-Romulan grandchild.
What the... I mean, for Spock it was a matter of survival, and David Marcus is a hunk AND a Kirk, so I understand those two guys, but Peter frickin' Preston? That kid's a shrimp! (okay, so he was shot by ship-mounted phasers and still lived for a bit, but still) The funny thing is, at least according to Memory-Alpha, the novelization for TWOK has Preston listed as 14. A little too young for some Saavik-lovin, I think.
Saavik was helping him with his studies (mathematics, IIRC), and they'd become friends. I don't recall the novel suggesting they'd become more intimate than that. The novel does have David and Saavik as sexual partners during ST II, which really complicates matters for the events unfolding in ST III. We learned in "Amok Time" that a Vulcan hitting pon farr for the first time must "mate or die".
That really confuses the issue. Was Spock in Amok Time a late bloomer? Because he's in his mid-thirties. Spock in The Search for Spock looks like he's in his early-twenties when going through pon-farr It's supposedly the same character... so why the change?