Silver and Shadow first met during the events of Sonic the Hedgehog (2006) when Shadow protected Sonic from Silver. Silver, mistaking Shadow for Mephiles, was confused by this, as Mephiles was the one who had given him the task to kill Sonic. Shadow and Silver fought until Shadow explained the truth about Mephiles and Iblis. The two went 10 years into the past, where they sealed away Mephiles and Iblis.
The two met later when they were among the ones appearing in Solaris' dimension. Shadow and Silver teamed up with others in this realm to find the Chaos Emeralds in order to resurrect Sonic. The two then turned into their Super forms along with Sonic to defeat Iblis.
Since the events of Sonic the Hedgehog (2006) were erased from the timeline, their original meeting never happened. Instead, they met in Sonic Rivals, where they started out as rivals as Shadow did not trust Silver's speculations on Dr. Eggman's identity. When Shadow found out Silver was right, the two teamed up. In Sonic Rivals 2, the two were rivals again and fought each other at some points.
In Sonic Generations, Shadow and Silver both appear as Modern Sonic's rivals. They later cheer the Sonics on during their battle against the Time Eater and attend Sonic's birthday party at the end despite being absent at the beginning. In Sonic Forces, Shadow and Silver were members of the Resistance fighting against Infinite.
Shadow and Silver have custom victory animations in some of the Mario & Sonic games. In the 3DS version of Mario & Sonic at the London 2012 Olympic Games, Shadow and Silver are the two Sonic characters of the Challengers group and they appear together in story mode. The pair has custom victory poses in Mario & Sonic at the Sochi 2014 Olympic Winter Games and Mario & Sonic at the Rio 2016 Olympic Games.
Shadilver is among the most popular slash ships in Sonic, but it is less popular than Sonadow. Shadow and Silver are often associated with each other by fans, but most of the time it is not romantically. On AO3, it is the second most written ship for both characters (behind Sonadow and Silvaze), although as AO3 does not have a great number of fanworks for any Sonic pairing, it does not fully reflect the overall popularity of ships.