I HAVE ADORABLE NEW ICONS |D
So it's a good time to get this mini-essay out of the way! This isn't going to be hugely long, but I wanted to ramble a little on my own feelings about Rise stuff to get more comfy playing her and explain my interpretation and so on. \o/ I think I will feel better once I do! Not that I'm having issues now, but that's partially because so far in camp (for her first week or two and then I had Real Life/RubyQuest stuff eating me and didn't get back to playing her for a bit) Rise's been getting Adjusted. Rise's one of those characters who needs a brief period to get comfortable with a situation before she really starts acting like the Rise we all know and love. So far she's kind of been too much like "WTF WHY IS IT 2009 AND WHY ARE WE TRAPPED HERE AND OMG SENPAI IS HERE!" to get eased into her typical routine of flirting, being nosy, raping Souji, and so on. (And again my unexpected not-hiatus didn't help that sob.) But by now she's kind of gotten used to things and will be pretty much settled in once she finally posts (which I will do this weekend if not today). So now's a good time to talk about--
RISE AND YOU: A COCKTEASE PRIMER
Or something like that. Watch out for spoilers but uh NO REAL PLOT STUFF, NOTHING SPECIFIC. So you should be mostly cool reading this. The only real thing that gets very vaguely alluded to is That Thing That Happens to Teddie on a Hot Day.
Okay, so the question at hand is along the lines of "IS RISE A HO?" Persona 4 is kind of weird in some ways because the relationship-building stuff takes place outside of the cutscenes/plot. So--there are certain bits of dialogue that don't change whether you're dating Rise or not at that point in the game. It creates this question of "So does she really act exactly the same around guys whether or not she's involved, or is the game just creating dialogue options that will make sense either way out of necessity?"
BUT in the end, all we have is canon to go on! I can't say things like "If Souji had rejected Rise by the time of the Culture Fest and the game knew that, this is what would have happened instead," because it's not true. I have to assume that she does in fact act the same whether or not she's in a relationship.
Most importantly, whether or not you choose to date Rise exclusively or otherwise, you(/Souji) are the only guy she's ever interested in, period. When Rise flirts with Yousuke at Junes, even if you're not dating her at the time and don't plan on it, there's really no argument to be made for "She's hedging her bets or planning to ask him out," because the rest of the game makes it clear--Souji is the only guy she has eyes for, even though she flirts with Yousuke too. (Notably, Yousuke doesn't react as if he believes her, which I'll get to in a bit.)
BULLET POINT FORMAT.
Rise is a flirt, especially if you show interest or she is interested. When you first meet her in the tofu shop, Souji--is mostly silent because he's Souji, Yousuke is an obvious nervous fanboy, Kanji clearly couldn't care less, and Teddie isn't with you. The people she chooses to flirt with throughout the game are Souji and Yousuke. Rise doesn't flirt with Souji until after you rescue her, so I'm assuming that it's your BRAVE AND MANLY DISPLAY OF FORTITUDE that gets her interested; she flirts with Souji because she actually wants to date Souji, and she's relentless about it. Yousuke she flirts with because it works and she knows it. She gets attention from him! She's not interested in him in the slightest, but he reacts well. Kanji has no reaction to her, so she doesn't even try. And Teddie . . . would probably take her up on any offers she made, so she doesn't try that either, because she's not looking for a makeout partner or a date (except in Souji's case). She's just having fun.
What it really boils down to is that Rise treats guys in the way that will get the best reactions from them. Yousuke is responsive to flirting without actually taking her up on her suggestions (like her feeding him, etc.), so she flirts with him. Kanji is more responsive to sisterly teasing than he would be to flirting, so that's what he gets from her. Teddie needs to be held at arm's length to prevent him actually taking her seriously and trying to ~SCORE~ with her, so she does. And Souji--well, GIRL KNOWS WHAT SHE WANTS and is relentless in trying to get it, but whether or not it works is up to the player. (The Souji in CFUD was responsive, ufufu.)
Rise is not a slut. She is a flirt, but not an indiscriminate one. Like I said, if she just wanted a good hot dicking, Teddie would obviously be willing, as would many other guys. And so she never comes on to them. She flirts with Yousuke because he reacts without responding. She leads him on, but IMO if he were actually to react in a serious "uhuhu yes Rise let's go feed each other all night" way, she would back off, because she's looking for guys to pay attention to her and react amusingly to her, not to break their hearts or end up with even more stalkers than she has already. It's all about the attention, not a willingness to sleep with them or date more than one at once, and not a desire to hurt them. RISE WAS A VIRGIN UNTIL SHE SLEPT WITH SOUJI. The end of her S.Link makes it pretty obvious that she's never been in a sexual situation before and that she does romanticize the experience, as opposed to seeing it as "Hey let's have a good time before Nanako gets home." Rise's not uptight about sex or repressed or anything; she has a strong sex drive and really enjoys getting a chance to exercise it, and isn't embarrassed of that. But she is also romantic! She waited until she fell in love to do it. It's not something she would do with anyone else. She wouldn't tolerate Souji doing it with anyone else either, but--
Rise is not a jealous girlfriend. Before the pageant, when Souji gets asked if he wants the girls to enter the contest, if you say yes, Rise tells you that she'd assumed you'd be jealous of other guys getting to see her in a bikini but you weren't that uptight after all. So clearly Rise doesn't see much reason to care about flirting and being looked at and all even when she's in a relationship. She still does it even if you're dating her. To Rise, things like flirting or posing in revealing clothing or whatever don't constitute cheating or any reason to be jealous. I think Rise is very much the "as long as you come home to ME at night" type of girl. She wouldn't tolerate Souji sleeping with anyone else, or making out with them, or making a serious effort to seduce them, but she's not bothered by Souji spending time with other girls or flirting a bit with them, and she assumes that he's not bothered by her doing the same with other guys. Souji is hers! She's confident in that. She's not bothered by him looking at the other girls in their bikinis either. She might tease him a little about it if it comes up, but overall, she's very open and not really jealous about that kind of thing unless it actually turns into something. Her constant glomping onto him is more a matter of her being assertive and direct in her attentions than "DON'T YOU DARE GO OUT WITH CHIE TODAY."
So--yes. She does act the same around guys whether or not she's involved, because 1. her flirting is not meant to be serious and is restricted to people whom it's safe to flirt with and 2. flirting is not a reason to be jealous in a relationship in Rise's eyes. Even if you don't ever date Rise, she flirts with other guys despite actively pursuing you and not being interested in them, so obviously she doesn't see it as hurting her chances with you/Souji at all. That's just how she is around guys, if they have the reaction to it that she wants, which is interest without active pursuit. If there's no interest or there is active pursuit, she will treat that guy differently accordingly. \o/
Oh, and when it comes to girls, everyone's fair game for a groping or a comment on their breasts if it happens to come up. :D