William Blake was very similar to other Romantics given his decision to fight against the Age of Reason. Blake found it necessary to protest conformity and war (characteristics of the Age of Reason given this period desired support of the war(s) and put down the importance of the individual). Blake was a nonconformist who believed that if his life was "created" by others he would have no true life to live.
I must create a system or be enslaved by another mans.
True to Romantic theology, Blake knew that forging his own path was the best choice for mankind. He held up many of the characteristics of the Romantic period: feeling over reason, importance of nature and imagination, and removal from corrupt/limiting societies.
While his poetry seemed to focus on the darker aspects of emotion, the texts still adhered to the characteristics typical of the Romantic Period. For example, in Blake's poem "A Poison Tree" anger is personified to represent both human physical characteristics and those of natural elements. Blake, like many Romantics, wanted to forge a new path for himself, idealize the individual, and use nature to reflect this idealization.
Blake's art was also representative of the typical Romantic. His pieces were overwhelmingly of individuals (while some did depict groups) surrounded by natural elements. These depictions also highlighted light as a main element.
While light seems to be an overwhelming element in his work, Blake also depicted darkness. One could interpret his use of darkness as a representation of what man should strive to remove himself from.
In "The Great Red Dragon and the Woman Clothed in Sun" Blake seemed to be speaking (in my interpretation when embedding the piece in Romantic thought) to the corruption of society and loss of individualism. The dragon represents a corrupt and Age of Reason ideology; whereas the woman, illuminated by light, must not bend to the more acceptable thought (societies) and pull herself away toward the light where she may then "create a system" for herself.
William Blake was a master of infusing his own individualism into pieces that would speak to those willing to listen and those wanting to pull away from the worn path. He embedded this thought into both his poetry and his art. While he did depict a darker side of the Romantic, he, nonetheless, depicted true Romantic vision.