Blaze and Silver do have a relationship, but the circumstances are complicated. In Sonic 06, they team up to fight off Iblis in the distant future. Silver trusts Blaze with all his heart and deeply cares for her, but Blaze calls him naive. However, Blaze likes Silver's naivety. In spite of all of this, Silver and Blaze's interactions in Sonic 06 would be erased from time. Because of this, they seemingly have no memory of each other. However, Silver and Blaze have interacted several times after this and work together very well. In Sonic Colors for the Nintendo DS, they meet each other on Sweet Mountain and fight against Orbot and Cubot, unleashing a combo attack of fire and psycho power. Sometime later, Sonic notes how they were perfectly in-sync earlier. Blaze notes how it felt like an easy fight, and Silver has the strange feeling that this isn't the first time that they have teamed up despite never having met before. (The memories are gone, but the feelings are still there.) Silver and Blaze decide to team up together to defeat the rest of the robots on Sweet Mountain while Sonic and Tails move on to the next attraction. At the end of Sonic Generations, Silver and Blaze can be seen having a friendly conversation at Sonic's birthday party. In the Mario & Sonic series, they have a special victory animation if they team up. The way they gracefully dance around each other is very flashy and coordinated. (Did they rehearse this, or are they that much in-sync?) Blaze has special victory animations with Amy and Daisy, and Silver has victory animations with Shadow and Yoshi. However, the animation that Silver and Blaze share together truly shows just how well they work together as a team. In the IDW comics, Silver and Blaze's relationship is strengthened even further. They interact with each other several times in the comics, and work well together. Notable examples include IDW Sonic the Hedgehog Annual 2019, when Silver is struggling to grow a garden and Blaze kindly offers her help, working together to make a thriving garden. They would team up again in IDW Sonic the Hedgehog #59 in the raid on Eggperial City. At one point, they find Shadow trapped in Fake Chaos Emeralds. Silver tries to free Shadow but he doubts his own abilities. However, Blaze encourages Silver, believing that he can do it. In IDW Sonic the Hedgehog #64, we can see Silver and Blaze's relationship truly take form. I highly recommend that you read it for yourself.