User blog comment:Omega natsu2/Chapter 369: The Place Prayers Reach, Predictions./@comment-2214433-20140129011112/@comment-24039250-20140131022655

NNN As for the theory regarding him and Gray I'm going with the "Father/Son" theory, because that would explain the scent. As for the reason why he despises Gray's name, it would be because it reminds him of his dreadful past. I theorize that during his time out in the world he fell in love with a woman (Gray's mom) and they get married and have a son (Gray). Several years later, maybe either leaving to get something, left to go on a journey, or simply while living in the town with his family, the town is attacked by a demon (Deliora).
 * If there I would bet that Silver was knocked out being off guard and when he came to (likely before Ur and Lyon showed up since they would have seen him there if it was after) he sees the remains of the town he lived in and cannot find his family believing them both dead.
 * If he wasn't there then he returned to the town after Ur and Lyon picked up Gray and found the town in ruins. Unable to find the remains of his son and wife, he believes them to be dead and he is devastated.

Blaming himself for his weakness to fall for humans and even having a family with them and since he is a demon which could have led the demon to the town, he leaves and tries to forget his past, feeling anger and sadness when he is reminded of it. It would explain the ruined town he was visiting and the grave marker that was there as well (possibly being for his son or wife). As I stated he still loves his family, but tries to act tough by regarding to anything about his family as "Disgusting" to hide his true feelings and sorrow. Either that or he heard that Gray lived and thinks that he abandoned the home during the attack and let his mother die, therefore angering Silver and is disgusted just hearing his name (Less likely but possible).