Would you consider the following behavior Jealousy or just Willie being annoying for the sake of it?
Neko does not enjoy cuddling with Willie in the room but on occasion he will be in the mood and can't help himself. Today I was holding Willie and rubbing him and Neko walked in and rubbed me. Since Neko rarely does this anymore I put Willie down and started petting Neko. Neko then layed down and i gave him a tummy rub. So then Willie walks over and goes straight for Neko's neck and bites there. i push him off of Neko and he goes to try and do it again but i block him so he goes away. Willie does this every time I give Neko a belly rub where he can see (since they both follow me everywhere it is almost always).
So is Willie being Jealous or is Neko's body position just really inviting to attacks from little brothers?