[ Jealousy ]

Valt Aoi
   Valt's rather oblivious to these kinda things, often not realizing what he's feeling or why he's even upset to begin with -- he should just be happy that you get along so well with his friends and everyone else. . . right?

When he does realize he's jealous (most likely when someone else points it out) he'll tell you - he'd struggle for a moment trying to express his feelings while trying his best not to appear pushy ( as he already feels bad by being jealous in the first place). 
  He's not the type of person to leave things unsolved so when the conversation starts he won't leave until their's a solution or an explanation, it'll almost always end in you two hugging it out and giving each other reassuring smiles.

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Shu Kurenai
Shu has probably felt every negative emotion that could even be named -- and jealousy was another ugly one. If he finds himself getting jealous, it ends up upsetting him more - being disappointed in himself as he sees being jealous as unattractive and rather unbecoming. Though he'll still try to stick closer to you more than usual as an extra precaution though he is rather scared of appearing controlling (which of course is never his intention).

Yet his not above glaring if someone is making an obvious attempt of getting him jealous (or angry) by intentionally coming on to you and his certainly not above calling them out on it.

He's protective, but he trusts you more than anyone so he knows that you won't stray from him so easily.

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Lui Shirasagijo
  Lui tries to keep his jealousy inside and under wraps; key word here being tries. He'll glare - not at you but pretty much everyone and everything else though he won't say anything other than an occasional 'tch'. He'll end up sticking closer to you than usual -- you'll quickly get the hint and try to defuse the situation.

Lui won't be the type of person to talk about it -- seeing jealousy as a strange emotion that just makes him look rather weak. If you do try to dwell into the subject, he'll mostly likely ignore it and avoid meeting your gaze until you finally drop it.

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Wakiya Komurasaki
Jealousy was always something Wakiya was familiar with -- from how he was jealous of kids who could be with their parents so freely, to him being jealous of Valt's ability to make friends so easily.

But even after feeling it countless times before it didn't make it any easier, especially with you -- he gets anxious about your relationship, his thoughts ultimately leading up to him wondering if he's even good enough for you. But if you confront him about it and give some reassurance -- then the whole ordeal with be quickly over and his back to his old sassy self.

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Alexander Shakadera
He's surprisingly hard to make jealous -- as much like Valt -- he's oblivious, as he doesn't assume someone is flirting with you; mostly seeing it as them being rather friendly. But if he sees or feels that you're getting uncomfortable he won't hesitate to get in-between and stop it from continuing.

He does get easily upset if he thinks your ignoring him (intentional or not) and if your spending too much time with his teammates -- if then he'll try to get your attention (sometimes rather extreme and stupid ways).

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Sisco Karlisle
Sisco can get jealous rather easily, and can a bit of an asshole about it too. He won't say anything up front about it and just glare at the person who he's jealous of (though he will give an occasional not so nice side comment if the person he's jealous is someone he doesn't know).

He'll never really admit that he's jealous (and will deny it to the bone) because doesn't want you to know, but he's not very subtle -- so you'd end up figuring it out faster than he can deny it, and if you tease him about it that'll pretty much get him off being jealous as he's too busy trying to ignore you (with red hinted cheeks).
+ PDA levels do seem to get higher if he's jealous.

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Rantaro Kiyama
Rantaro won't beat around the bush if he's jealous; he'll be very vocal about it -- maybe even to the point of annoying (but endearingly so).

He'd probably / most likely be whipping out his gigantic fan and end up challenging people into a battle. But even with that said he does has enough confidence in himself and an over abundance of  love and trust in you, that he knows that you won't leave him so easily.

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Naoki Minamo
For a geunis. . . his dense. It takes him a good while before the thought of jealousy even crosses his mind. As he just assumes the person flirting with you is just being overtly friendly (as he didn't really know the difference).

For once he finally realizes his actually jealous and he will try to one up the person who he thinks is trying to 'steal' your favor, an attempt to seem as the intellectually superior (which he is) to whoever it was.

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Phi
O h  b o y
Phi does not deal with jealously very well -- but he's not one to lash out -- what he does is a bit worse. If he can (which he almost always can) he'd manipulated the situation so that he can be closer to you. Though of course he  never really does anything that can hurt you -- and if you do say you want to be with your friends -- he'd agree. But he'd still probably keep his eyes on you (he trusts you plenty it's them he doesn't trust).

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Hearts
Much like his brother he's not good with dealing with jealously either but most of the time he'd across his arms, and scowl all while making some sassy side comments and him trying to intimidated what he perceives is his 'rival'. He can be a bit whiny, wanting your attention to be more on him than anyone else but if you talk to him about it he will try to keep his jealousy in check.

Though to get your attention he'd probably do something he thinks you'd like (even some of them can be borderline dangerous, making you worried for him more than anything else).

[ note ]
hopefully that didn't suck ;-;
really sorry if it did :<

anyone want a part two? since I only did a few of them.