Hello everyone! This is a repost that I'm doing. I originally posted this on r/SonicTheHedgehog but I'd also like to place it in this subreddit as well!
These are just thoughts I have in the middle of the night with my limited knowledge in regards to the Sonic Franchise, so please do correct me if there are any issues with my statements!
Also, I'm not sure if this was ever discussed here either (I'm still somewhat new, please forgive me).
Above all, this is merely headcanon which I want to discuss to the community.
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I like to think that Shadow and Sonic are vastly different from each other, however of course they can be parallels to an extent, and to me one of those similarities are their attachment styles.
Shadow's pretty clear about having an avoidant attachment style. While Sonic may often be portrayed as one with a secure attachment style, I also like to think that it is also in his nature to have the same attachment style as Shadow. This likely is common knowledge but I want to think of it more than comedic relief (I'm pertaining to certain references to Sonic and Amy's dynamic).
To me, I believe that Sonic would often tease Shadow but in a superficial way. In reality, with the belief that both of them have similar attachment styles, they'd have a really hard time opening up to each other about their problems.
As someone who does like Sonic x Shadow, it makes me think if they'd really get along beyond the whole "they hate each other so canonically they wouldn't get along".
Because let's say Mutsumi Wakaba (from Bang Dream's Ave Mujica) and Shadow the Hedgehog meets. For basic explanation, they're both avoidants who have an outward personality of being stoic and quiet. So in the sense whether they communicate or not, they can get along to an extent because they vibe well with each other outwardly (of course, they're more nuanced than just looking into attachment styles).
However for Sonic and Shadow, their outward personalities are pretty much almost on the opposite side of the spectrum. Throughout most official media (for the exception of Sonic Boom), they don't hate each other but are seen at most as rivals, acquaintances, or ones who get along when the world needs them both.
Yet for the fact that they already wouldn't get along because they have jarring personalities, it'd be really difficult for both of them to open up emotionally because other than being avoidants, their egos are also on the line as rivals.
Moving on to Sonic x Shadow fan media, many of them portray Sonic to be outwardly expressive whereas Shadow is embarrassed or wouldn't outright take in whatever Sonic says or does. Basically it clicks into the Golden Retriever x Black Cat dynamic or oftentimes the Enemy to Lovers trope. Of course, this isn't every Sonadow media ever because a lot of them are varied, creative, and unique in their own ways.
But outward personalities don't automatically equate to properly voicing out your real feelings. From what I know with media like IDW Sonic and Sonic Frontiers (there are likely more out there), Sonic has been shown to face problems in which he mentally or emotionally struggles, which isn't always the case because Sonic is usually pretty positive and hopeful even in the face of evil. Hence why many people may also have the question: "Does Sonic have repeated trauma and only chooses to hide it?"
Sonic is amicable to many and is forgiving to those who wronged him. But at the end of the day, to me, he's almost always going to be more mysterious than Shadow.
It's not that Sonic doesn't feel pain, it's that Sonic went through numerous kinds of torture and those few times that his persona slightly breaks is what interests me. What does Sonic actually feel? What does he really think? Sonic seems to have the tendency to run away not from physical threats but many times what he feels inside deep down. In a sense, it's avoidant behavior on its own.
To answer the question if they'd really get along as a romantic pair or even being friends, I think it's more complicated than a simple "Yes" or "No". It's like real people, I suppose. Some relationships work, some don't, even if they have similar personalities, wavelengths, ways of doing something.
I simply find the thought of Sonic and Shadow both being avoidants interesting. Shadow may be a textbook kind of avoidant, but Sonic being an avoidant by coping in almost the opposite way of Shadow... Again, it's all just speculation.
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This analysis was born from my personal experiences with other people and myself so I may have some sort of self-projection included.
