UPDATED: Horns Removed from Seal.

Trivia:
Because their colors are the most similar, They actually take the initiative in fooling one into believing that one is the other.
Despite their obvious differences, Dev-Ill and Seal can perform each other's duties rather well.
Seal is more powerful physically than Dev-Ill, but lacks the demeanor to demonstrate it on her demonic partner for any reason...Except one.

More Info can be found in their Bio;