I've already talked about this before. This was a rambling mess but it will do for now...you get the gist
-Jonathan was always babysitting Will except when he was working/at school -We know Will was always hanging out with the boys Meaning that Jonathan [when babysitting Will which was always when he wasn't at school or working] was always hanging out with the boys. -The boys love Will and will do anything for him. -Jonathan loves Will and will do anything for him. -Jonathan and the boys love and appreciate one another because of that -But theres an extra layer of appreciation here to the point where they think the other hung the moon/and think of each other as super heroes. They think of Jonathan as a super hero and Jonathan feels the same about them: because Will is treated like garbage by everyone in Hawkins, including Will and Jonathan's own father. They think the world of people who show Will the love and appreciation that he deserves. Meaning each other. Thats just basic common sense. Why wouldn't they love and appreciate each other for that when its clear they all love Will and would appreciate anyone who was there for Will.
-The boys especially love Jonathan and look up to him because he is Will's fiercest protector and does everything for Will, while Lonnie was such a disappointment and was horrible to Will [and most likely them too] Jonathan does everything for Will. He is constantly sacrificing everything to make Will happy. He always put Will's [and Joyce's] needs and wants before his own. Lonnie and everyone would treat Will like dirt, but Jonathan would go out of his way to constantly remind Will why he was so special and the person that mattered most to him. They'd have a deep appreciation for Jonathan also for being the opposite of Lonnie, Jonathan was the person Will needed
-Jonathan was the cool older brother who didn't conform to what Hawkins wanted them to be and encouraged others to be who they were/their true selves.
-The boys loved J also because Jonathan didn't expect them to change for him in order to get his approval like everyone else did, Jonathan just loved the boys for being special and unique and different. The rest of the town might have treated them like freaks, but Jonathan treated them like they were special and important because they were. -And they'd love Jonathan most of all because Jonathan is like Will's parents constantly sacrificing for WIll's needs and wants and happiness. Why wouldn't the boys adore and worship him? -Its also about Jonathan and the boys values. They hate the townspeople of Hawkins for hating anyone that is different. They themselves are different. They're all against conformity. Jonathan shows he values and appreciates ppl for being true to themselves and not giving into what society wants/pretending to be someone you're not just so you could fit in and be popular. Jonathan values love and friendship over what the rest of the town values. Which is money, appearances, popularity ext all the stuff this show teaches you doesn't matter and that you should value love and friendship and being loved for who you truly are above all else.
-Mike and Jonathan are the closest. Mike is Jonathan's little co-pilot on this magic carpet ride. And its nothing against Dustin and Lucas. They are just much closer because they've known each other so much longer- Mike was Will's first best friend, so Mike and Jonathan have been through a lot more hell and battles together fighting Lonnie ext and only had each other to lean on back in the early days of their 'Will Byers protection squad' And ofc why wouldnt Jonathan appreciate Wills first best friend who loved him as much as he did.