- Rouge the Bat - as one of his closest friends and a member of Team Dark, Shadow is rather protective of Rouge, though he does attempt not to show it in favor of keeping a stoic expression on his face. However, much like Whirlwind, he has also shown some distaste towards her flirty mannerisms at times and often stays out of her occasional heists.
- E-123 Omega - another close friend of his and his other teammate in Team Dark, Shadow is also protective of Omega.
- Sonic the Hedgehog - while the Blue Blur will forever be Shadow's arch-rival, the two are also steadfast allies and close friends. That said, there have been times where Shadow can't help but groan at his blue friend's occasional idiocy, and the two can still get on one another's nerves on occasion.
- Miles "Tails" Prower - Shadow is very appreciative of Tails' engineering and scientific genius, such as when he was able to make a new pair of his Air Shoes when his old pair eventually broke down. He's just not too fond of the fact that even the youngest member of Sonic's team managed to grow taller than him.
- Amy Rose
- Whirlwind Reyes - a fellow soldier in GUN's Armed Forces, many consider Shadow to be the Yang to Whirlwind's Yin, in that the former is the more quiet and serious of the two while the yellow hedgehog is the more open and laid-back of the two. They sometimes get into arguments over certain matters, and Whirlwind has shown to be greatly annoyed with Shadow's behavior at times, but they still have each other's back whenever possible.
- Knuckles the Echidna - The red echidna and black hedgehog do not interact with one another often, but are often allies when the situation calls for it regardless.
- Zagan the Gravebringer - a mercenary with incredible power, Shadow and Zagan may be on the same side - at least for the time being, but they haven’t necessarily interacted all that much.
- Dr. Eggman - though technically a relative of his due to being related with both Professor Gerald and Maria and was once even on his side - albeit for his own agenda, Shadow has since become an adamant foe to the mad doctor in his eternal vigilance in upholding his promise to Maria. Thankfully, his absence during the last decade means that he hasn't been an issue for quite a while.
- Infinite - the mad doctor's prime soldier during the events of Rage Against the Empire, Shadow blames himself for being the one responsible for being the cause of what the monster that the former mercenary became and, by proxy, paving the way for Eggman's unexpected domination over the world.
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