Unlike towards her blood brothers, Sakura doesn't seem to mind having Raidyn around. She's come to understand that he needed their family and that he cherishes it very much. Because of this, Sakura actually appreciates having Raidyn around.
Raidyn has an indescribable relationship with Riggs. Maybe it's because it was Riggs that saved him, or that they're both orphans. But he's very close to Riggs, like they were actually blood brothers. Even though they aren't, Raidyn likes to think they are. He never wants to be separated from Riggs, and is always seen with Riggs, whether it's between his legs, on his back, or just by his side.
Maybe it's because they were both orphans taken in by the same family, but Riggs is very close to Raidyn. He saw a lot in himself when he first found Raidyn, and doesn't want the mothkitten to have to live the same pain that Riggs had to before Cyrus came into his life. Riggs is more of Raidyn's legal guardian than Cyrus and March, which he's fine with. He'd do anything for little Raidyn to be happy.
Raidyn can get... annoyed with Lysander. His adopted brother is very energetic, which is the complete opposite of Raidyn. Due to this, he doesn't interact with Lysander as much as he could, and, in fact, sometimes tries to even avoid Lysander. Raidyn loves his adopted brother, but Lysander can get to be too much for poor Raidyn to handle.
Lysander wishes that Raidyn would open up more. He's like a lump on a log, and Lysander doesn't like it. There's already two others like that in the family. Because of this, Lysander constantly pesters Raidyn, trying to get him to be happy and take part in some of the games the other kittens play. Although his efforts are all in vain, Lysander refuses to give up, and is always ready to try again.
Aside from Riggs, Raidyn seems to get along with Demetrius the best. Maybe it's because they're both overall grumpy and somewhat sad mothkittens, Raidyn's not sure. But he can always relate to Demetrius in some way or another, especially when it comes to Lysander's rambunctious behavior. Often Raidyn can be found talking small talk with Demetrius, and being comforted by his adopted brother's silence.
Demetrius is comforted by Raidyn's quiet nature. He's not energetic, not rambunctious, and certainly not always trying to ruin Demetrius' day. Because of this, they get along quite well, and they enjoy each other's company in silence. Demetrius appreciates his adopted brother's fears, and is always there to help him through them, as well.