Can't be mentionned without spoiling Season 2's premiere, but really worth it : When Sparadrap has to create a new avatar and Omega Zell (only guild member available for it at the time) refuses to help him level up, Ystos shows up to help him and invites him into the Justice guild to be able to do so. Once that happens, Sparadrap's first reaction tell the news to his brother who's using a laptop in the same room as him:
Kevin: This is so cool! Do you know what just happened? I just joined the Justice guild! That's the most super strong guild in all Horizon 1.1! You must not know about it. You don't even know how to play.
Thomas: Do you do this on purpose?
Kevin: Do what on purpose ?
Thomas: Haven't you worked out the identity of Ystos the druid ?
Kevin: Err... no.
[Kevin goes back to playing, cut to in-game]
Ystos, to Sparadrap: It's me, Thomas.
[Kevin turns away from his computer with a very surprised look on his face, looks at his brother's laptop over his shoulder, than back at his own computer]
Kevin: Wow... That's super neat! I was such a great Horizon 1.1 player, you've manged to reach level 100! I'm such a good teacher!
Thomas [sighs]: That's right. Now, let's do the Mortegarde dungeon.