Oh my goodness I want to hear your headcanons for my main three hedgehogs, Sonic, Shadow, and Silver!!!
I’ll limit myself to one, defiantly not because most of my small list-worthy headcanons go to Sonic.
I noticed after writing that this that all of these have a very strong link of home. And are less directly headcanons for some and more so… headcanons told through how the characters act through a rough story.
“Story,” as in I was trying to make these just be headcanons but I desperately want to tell stories so it’s like a very apprehensive approach to story-telling
Sonic found Tails on the island he himself had grown up on. He had landed the Tornado after an adventure to check up on his old home and, mostly, to drop off some junk.
He has a burrow tucked away on that island, one where he used to sleep before setting off in favor for his nomadic life style. Now he uses it every now and again to store his things. Little trinkets and souvenirs from his battles and trips around the globe. 
When he got back to his Tornado, he found Tails checking over the biplane… fixing damages from Sonic’s less-than-perfect landing in the sand. He watched him tinker for a while- Why not? Free repair!- before stepping in and confronting him.
Tails explained he was looking over the plane, upgrading it, even, and that he was, “so so so sorry, mister!” Sonic just shrugged him off and told him he seemed like a nice kid and he could totally make his plane faster if he really wanted to, but that Sonic would be taking him straight back to his own home afterwards. Win win win, in his books! He gets a new plane, the kid gets to fix things up, then Sonic can just drop him off and be on his way!
After repairing the plane and dragging the kid around the island, looking for his home or for someone to stick him with, is when Tails dropped it on Sonic that he didn’t have a place to go.
After that and a lot of convincing, Sonic eventually decided Tails could tag along. “For now,”
Sonic can barely land a plane. He always gets it done in the end, but he never goes slow enough to land delicately.
After Tails grew up and started going on adventures of his own he stopped by his home-island after getting the name of it again from Sonic. There was something there that he used to make a machine when he was younger and he’s never been able to find anything quite like it.
While he was searching, he found a burrow. “More like a cave,” filled with… things. Not useful things, but so many things. He hadn’t figured it was that special, he wasn’t even sure if it’s owner was still around or was even trying to keep these things hidden, but he was curious about it and made sure to keep mental note of it.
Weeks later, he brought Sonic to it on a casual, “Let’s go find something fun,” adventures. Tails was still weary to do anything more than poke his head in and look around, so he was quite surprised when Sonic laughed and jumped in.
That’s how Tails found out that he and Sonic grew up on the same island and he had never known.
When Shadow was still aboard the Ark with Maria, he was expected by Gerald to sleep in a designated space. It wasn’t out of any cruelness from the Doctor, but just out of worry of Shadow as The Ultimate Life Form.
His “room” was the laboratory, with his suspended animation chamber. His “goube tube,” as Maria labeled it, and as Shadow and Gerald themselves also called it. It was simple. A space for research and experiments and study. One of these experiments did include observing how long Shadow could stay awake for and the effects exhaustion had on him. The Doctor still wasn’t so cruel as to not give him a bed, though. A little basket of one, thick blanket that Maria had donated was kept tucked away when not in use. It was less than comfortable, but Shadow wouldn’t know.
Not until one of his nights where he was left to free-roam lead him to Maria’s room. She would regularly sit in the hallway and wait for Shadow to pass by before bed when she knew he was out of the lab. And she would always pull him in and pull out the spare mattress comforter tucked away under her bed, dress it with a fitted sheet and a pile of her stuffed animals and cozy throw-blankets to make a nest-like bed for Shadow.
He would always start up Maria’s night time machines for her while she fixed the bed. Then he would lay down, telling himself he was simply waiting for Maria to fall asleep, that he was keeping a protective eye over her, to make sure she was alright and then he would get back to his self-employed patrol.
He’d always end up falling asleep.
Now he makes burrows for himself whenever he has the rare opportunity to sleep on a bed. They’re never quite the same.
Silver has abandonment issues, end post.
He’s never known a future where he’s had the chance to know his parents or even a family. It’s always been too complicated, he’s tried, to figure out how he is still always him no matter the changes he makes to the past. Sonic would tell him something along the lines of, “All you can do is be happy that you’re you; That you’re alive, here and now,” and he has, much to the irony that, “you can’t live in the future or you’ll miss out on the present,” held.
Silver also never really tried to find his family, whenever they might’ve been at any time. He figured that if he had one in his newly-saved future that they would find him. Besides, the thought of knowing who you’ll be losing if you don’t keep the future safe sounded far too painful.
Bonus: ‘06 except I’ve only ever seen the cutscenes via Snapcube’s dub
In Iblis’ future- Silver’s present as we see it in ‘06- he was truly alone. How or why he managed to survive, he never really knew.
But he at least thought he had always had Blaze. They met in the city we see in ‘06. She just seemed to be a lone surviving fighter, like Silver, and they stuck by each others’ sides since.
It was comforting through the entirety of the game to have someone Silver thought was fighting for their home, too. Fighting for his home.
And it broke his heart when he found out it had been nothing more than the Sol Emeralds that sent Blaze to him. The emeralds that brought her to his present. And while, no matter what, he had made a genuine friend it was still shattering to know she wouldn’t be waiting for him when he finally fixed the future.
