I probably should have done two different posts, but... eh. This is for Rue and for Shaun because she asked.
First off, Cesare is straight.
By that I mean that he, if he was using our current definitions of various sexualities, would identify himself as heterosexual without a second thought. It's pretty much a non-issue for him. Canon has delightfully chosen to show me his reaction to girls and kissing girls and seeing girls with their breasts all out. (This is a first in any character I've ever played and I'm still basking in that hilarious afterglow.) Cesare likes flirting, making out, and having sex with girls. He's sixteen years old and shows it.
However (and this is a big "however"), he is not so obsessed with them that they're the most important thing, or even something close to the most important. He is capable of turning off the hormones when he wants to--or at least ignoring them--and it takes more than just a pretty face to get him really interested. That is to say that Cesare is not really interested in girls. He's interested in them in a fairly superficial, excited, playful way. It's not the same as his Interest (with a capital "i") in his family's position or in the political situation in the peninsula. He wouldn't want to give up flirting with girls because that's something that he likes but it's also not something that is at any risk of taking away his attention from more important things.
A lot of this has to do with the dynamic between men and women at his time. It has been argued that there are two "fault lines" in his society that separate adults from children and men from women (both times with the prior given additional importance). Cesare is right at the cusp of crossing the space between child to adult and he is very much aware of this. He is also very aware of how his relationship with women is changing as well and how the power is moving in his direction. Cesare's canon is incredibly male-centric--I think the only female character who could potentially ever be appable is Lucrezia. This is to be expected since a lot of it takes place in areas that, quite frankly, did not have any women in them. A story about a university in 1491 isn't going to have many female characters. It reflects the fact that Cesare, like most young men of his day, tends to interact with other boys and men. Canon!Cesare is remarkably liberal but he's still a product of his times. As much as he respects his sister and urges her to do things that would typically be inappropriate for a young noblewoman, he also knows how the gendered relationships play out and he understands what his part is supposed to be. He's good at playing it, even if he doesn't always agree with it.
So... That's about it, really. Cesare is straight. You can stop reading now unless you want the convoluted attempt to explain Rue. :|b
Cesare likes Rue and I think I need to just stop trying to put a label on it. I rambled the other night about amor cortés in comparison to other types of love because I was trying to get a handle on what to even call their relationship. I just don't think I have a term for it. It's not amor cortés because (ignoring, for all of this of course, the fact that they're really all talking about heteronormative relationships and I just don't even want to get into that yet) that involves the placing of the other person up on a pedestal and really has more to do with the chase than the attainment and Cesare is not particularly interested in living up to its requirements. The part that is similar is the fact that it is looking at love as a game--but I'll come back to that later.
I briefly considered it as something closer to just lust, but that's really not right. Cesare thinks Rue is beautiful but he wasn't immediately attracted to him in the same way as he is immediately attracted to various girls in canon. (But at the same time, Rue looks feminine enough that it works for him. Cesare knows Rue is male and he uses masculine endings and etc when he talks about him--not that you can tell with the translator--but it's all androgynous enough that especially if he can assert his dominance it's not a problem.) It's a different sort of attraction, some sort of weird blending of emotional and intellectual connection with whatever physical-ness is there. Because it's not just (or primarily? idk words) physical it's taking longer to build up but is already surprisingly permanent. If Miguel or Angelo or someone Cesare was familiar with and had as a part of his inner circle was in Camp I don't know what would have happened. Frankly, he needed Rue. Needs. He's too young to really stand on his own and he's so out of his element that he's much more willing to make real connections instead of the superficial or political ones he usually forms.
I go over their relationship a lot because I'm so concerned I'm doing something wrong. It's weird. The whole thing is weird! Canon is not obviously helpful and I get afraid that it's just that I find the CR adorable sometimes! But... I'm coming more and more to the conclusion that the whole thing is out of my hands. Something about Rue is just clicking with Cesare (actually, it's a bunch of little things that are joining together and combining into a Big Thing). He loves his company and spending time with him. It's overriding issues of gender or sex, made possible by the fact that girls are only interesting to him in the first place anyway. Cesare sees a difference between a sort of all-engulfing love and a more playful and flirtatious one. The latter is safer. It's a game, like how amor cortés can be, and it's one that he is willing to toy with. In that sense, Rue is filling in the position usually taken up by some cute girl and even doing a better job of it because he is both useful and safe and his importance is heightened by the fact that Cesare finds him genuinely fascinating. I realized how important Rue is to him in the truth post when Cesare actually wanted to talk to him even though he hated the effect he was under and was in such a terrible mood in general. Most people would have gotten some form of "gtfo" in varying degrees of politeness, which was very close to what Cesare told him except he couldn't because he wanted him to stay. That whole thread was kind of magical for me because of how willing he was to have it. (In comparison, the truth thread with Shaun led to Cesare fuming over how to kill him.) Cesare wants Rue to know about him, at least more than he already does, to the point that he was willing to talk about himself and his family while under the truth effect. The other thing that brought home to me the importance he's placing on this CR was when he asked Rue to call him Cesar. I was really nervous about going with that because tl;dr headcanon issues that I already explained anyway, but it felt like the right time. Cesare has a lot of barriers up but the right person can slip through them and do so relatively quickly. It's a... big deal that Cesare asked Rue to call him by the Spanish version of his name but his falling asleep at the end of the thread, especially after expressing out loud (of course, not in a way that would really make sense to most people l-lol) how much he likes Rue was almost more significant to me. I want to check something about this before I really tie up this train of thought, but that will have to wait until the next time they thread, so I'm just going to end this here for now. o/;
Ed Okay, coming back to this quickly to just say that I was surprised. I thought something might be triggered by the use of "Cesar" in the place of "Cesare" but tbh he's barely noticing it now. It feels very normal and expected. I suspect this is because he's switched over to Spanish when speaking to Rue (a-again, not that anyone can tell) and that's the form of his name that he would expect to hear then, anyway. Rue is one of two people in Camp who he technically speaks to in Spanish. I think it's cute. xD;
In tentative conclusion, I don't have a term for what's going on there so I hesitate to call it one thing or another. It doesn't really fit any of the things I've tested it up against, but it's important and I like it. :) Rue is doing something right and I expect that Cesare will continue to get sucked into this game until he suddenly realizes how real it's gotten. Maybe he'll figure it out on his own sooner. I don't know. The boy is smart but not very good with emotions.
TL;DR
If that made zero sense, I can try to explain better. :|a
Ed ............I feel compelled to add in that the first section was because it came up in conversation and was interesting. The second half was basically just me going "well, if I'm just going to be mentally going over it every time someone presents on love/sex/etc in his time period, I might as well put it somewhere."