Mothers Day...

is the only day that Chaos will eat cookies while crying through out the year. He's sitting by his foster mother's, Nekomi's, grave, eating chocolate chip cookies, which were her favorite and giving her one as an offering. Which her spirit is happy to accept.

Reason he and his siblings don't do anything for their real mother is that they were never loved by her and were only kept around for her status, so Chaos found Nekomi and made her his foster mother and finally felt the love of a mother. He was heartbroken when she died and is now found with his older sister, Flare.