User blog comment:Shadow001/Secrets/@comment-252417-20111119072954/@comment-201.54.48.6-20111125161033

I don't think it is a filler ep, because Secret is a canon character and member of the Young Justice comics. If you read the comics, Secret was the reason the group was created and she was the most important character at the last two comics issues (#54 and #55), when she allied with Darkseid. So, I think we will it is possible to see Secret joining the Team before the end of the first season and, if Darkseid appear at the second season, "Doug Side" can want Secret join him... But it is interelly possible that they don't follow the original comics.