The Joker:
He can get stressed out when it comes to failure and flaws in his plans, he is a perfectionist in a chaotic way. When he gets stressed you have one solution, it might sound dark but since it makes him happy you bring him someone to torture, people are rather easy to get. It makes him laugh and it makes you happy to see him easing his stress.
Dr Jonathan Crane:
He's pretty good at hiding it when he gets stressed, but in the rare moments when he does show it, you try to stay away, you don't want to make it worst. He always tells you something along the lines of "you don't need to avoid me, I would much rather have you around right now." Which is then followed by you giving him a big hug to help him calm down.
Roman Sionis:
He gets very stressed very often. Between dealing with people crossing him and just getting stressed out by his thoughts he seems to be upset often. To deal with his his troubles, you go up behind him and wrap your arms around his waist very gently giving him a comforting hug, you usually whisper "I love you" or "it's alright." as you do.
Two Face:
Distance seems to be the key. He loves you, but when he is stressed out he can get a bit mean and it's best for the both of you just to stay away from each other. When he is calm he usually goes up to the bedroom you two share and talks to you for a few minutes, and it ends with a hug or a kiss.