She is startled, at first, which is - incredibly stupid, in hindsight, she told Mhalir she thought he was gay but she revised that, today, when they sparred - maybe he just needed to feel like he'd earned it, which would actually be very cute and - kind of Mhalir, if you extrapolate him human.
She kisses him back, while all this flickers through the back of her head, because whatever feelings she's having she can have them just as well while not making mistakes that'd be dangerous. (She does not specifically believe Ma'ar to be dangerous, they're on Mhalir's spaceship right now, he could maybe pull something off with the mind control but it'd be an incredibly astoundingly stupid thing to pull just to have Carissa and she's sure he wouldn't. But her instincts about this are not at all tuned to being powerful or having options, practically none of her instincts are tuned to that, her instincts are entirely tuned for situations she might've gotten into in the army or in school and in every conceivable situation the thing to do would be to respond, nicely, while she considered what she was going to do.)
(She finds him attractive, she likes it when he touches her. She is all but considering this irrelevant; it is definitely secondary to a dozen other things.)
Last night, what was the plan? The plan was to see if seducing Ma'ar cheered him up, which would've been a pleasant turn of events, though not one she wanted in the kind of fashion where she was willing to actually herself take actions towards it - it's safer, right, if Mhalir is doing it, though right now he's quiet in the back of her head, presumably considering this to be mostly between Ma'ar and Carissa - unless Ma'ar used magic to hold him back, like during the sparring, but - no, she evaluated the odds of that and concluded it'd be ridiculous, she doesn't need to revisit it five times. He's not stupid.
What's the difference between telling Mhalir it'd be neat if it worked to seduce him, and - doing it herself? Doing it herself- betrays more, exposes more vulnerability - there are more possible girls who give in, here, than girls who seduce him, it's offering him more surface area, it's giving him things she wants, it's dangerous to give people a picture of what you want, it's far more intimate than merely sleeping with them -
- this doesn't have to have a lot of surface area. It can be nice, and safe, and fun, and she can know what it'd be like if Mhalir were human and she doesn't need to have any feelings, and if she decides to tomorrow then that's tolerable, it's less vulnerable if he's not right here. (And she ticks down a list of possible feelings, to screen out the stupid ones. She is not going to care if he's had better, he has an army and he has a mage breeding program and he's twice her age, of course he has, it'd only matter if she were trying to locate her self-worth in this, and she knows what she's good at; it's magic. She is not going to care if he doesn't, actually, like her; Mhalir needs her, she doesn't have much information about what he'd think of her otherwise; it would be interesting to know, and there isn't an answer that's scary. Maybe he ...wants to hurt her? That's fine, sometimes it's fun and if it's not it's good to know where the lines are. What even feels, here, like she might have feelings about it tomorrow?)