edit: to pirateking obviously
It's was a running joke on his Formspring that Vriska is Hussie's favorite character and he was going to marry her because she is so fat. (no it doesn't make sense)
Or if you mean from an in-comic perspective, the character of Andrew Hussie is part of the story, and after he died he met Vriska in a dreambubble and proposed to her (probably influenced by the gag above). It's canon, too, since Vriska references it later after Tavrisprite happened.
Homestuck.
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