May I join in? Sorry, this is my first time in the forum, too, so I hope I do this right. I'll use Jonathan and Simon (Sunny), since they're my favorite couple.
Which fictional couples could they be compared to and why
I'm not entirely certain which actual couple I could compare them to. I suppose they fit a sort of Sherlock-Watson dynamic, but neither are sleuths or doctors.
Who takes more responsibility for their actions/who's more ready to give in and compromise?
Sunny is likely to take too much responsibility for his actions, feeling guilty in situations where he is not at fault or in which he had no control. Jonathan willingly accepts the consequences of his actions, knowing he caused them, but he usually feels neither guilt nor a particular obligation to make amends.
Sunny is stubborn and does not wish to compromise, but he typically loses to Jonathan in contests of will and typically is the one to yield. Jonathan takes "no" as an inconvenience to be worked around.
What negative traits do they see in the other, and how do they deal with it?
Sunny sees that Jonathan can be callous and manipulative, and he also Jonathan's disregard for his own well-being.
Sunny constantly butts heads with Jonathan about his negative traits, often compelling him to find more peaceful or innocent means to his ends, and Jonathan, when he is feeling amicable, will oblige him if possible.
Jonathan sees that Sunny can be hot-headed, reckless, and, at times, naive.
Jonathan actually exploits Sunny's traits for amusement, baiting him over something silly in order to watch him get angry, or for matters of greater importance, such as pushing him past his boiling point in order to trigger his "Berserker" state. On the other hand, Jonathan also finds Sunny's naivete to be charming and will sometimes go to great lengths to preserve it.
When did they realize they were attracted to each other, and how did they deal with it?
Sunny hates Jonathan for quite awhile, disliking him from their first interaction, and it is because of this hate that he refuses to acknowledge any attraction to Jonathan. However, as the story progresses, he realizes that he actually cares quite a bit about Jonathan and they become friends and eventually a couple (in their own sort of way.)
Jonathan casually flirts with and teases Sunny with shows of affection almost as long as they know one another, and he plays along with Sunny's eventual attraction to him. However, after awhile of pretending, he realizes he actually cares for Sunny back. He views this development with fear and frustration, worried it will hold him back in his revolution, but, though he tries to bury it, he is happy, too.
What are their mannerisms when walking side by side
At the start, Jonathan tends to walk a step ahead of Sunny despite their height difference (Sunny is considerably taller) and tauntingly dances out of reach when he teases Sunny to the point of rage. Sunny keeps his chin raised and lets Jonathan talk to the side of his head, never looking at him head on, and they both are distanced from one another.
When their relationship develops though, they gradually gravitate towards one another and exchange more eye contact. Eventually, Jonathan stops walking in front and walks more equally and relaxedly with Sunny, sometimes even leaning on him when particularly tired. Sunny does not hold himself so tall and leans in slightly during their conversations
How does being around each other change their thought processes?
Initially, being around Jonathan makes Sunny frustrated and angry, neither which are conducive to careful though. However, Sunny begins to understand Jonathan and people in general better, and being around him allows Sunny to better control his anger issues.
Sunny starts out as light entertainment and a vaguely useful asset to Jonathan. When their relationship deepens, Jonathan finds his thoughts more relaxed and distracted, something that worries him and makes him fear that Sunny is a hindrance to him.
How do they show affection?
Sunny shows is affection gruffly, almost tsundere style. He would die of embarrassment if he had to say, "I love you." In the end, he ends up showing respect and affection to Jonathan by spending time with him.
Jonathan easily tosses "I love you's" and cuddle-ish gestures at his companion, but he does so with complete lack of care, investing no real emotion in the gesture. His greatest shows of affection come when he actually indulges Sunny's wishes or calls him, "my dearest idiot," high praise from him.
Have they discussed the future? Why/why not?
They never truly discuss the future, though they both have a mutual understanding of what is likely to happen (not going to go into too much depth. The plot isn't completely set in stone yet, and I don't want to ruin it by constraining it too early). Sunny does not want Jonathan to throw his life away, and Jonathan does not want Sunny to stop him from doing what he needs to do. Neither particularly relishes the topic, so in order to enjoy the time they have left, they avoid the topic altogether.
Thanks for the questions. Sorry if there were typos or grammatical errors.